Martin Luther (10 November 1483 – 18 February 1546) was a German priest and professor of theology who initiated the Protestant Reformation. Strongly disputing the claim that freedom from God's punishment of sin could be purchased with money, he confronted indulgence salesman Johann Tetzel with his The Ninety-Five Theses in 1517. His refusal to retract all of his writings at the demand of Pope Leo X in 1520 and the Holy Roman Emperor Charles V at the Diet of Worms in 1521 resulted in his excommunication by the pope and condemnation as an outlaw by the emperor.

Luther taught that salvation is not from good works, but a free gift of God, received only by grace through faith in Jesus as redeemer from sin. His theology challenged the authority of the pope of the Roman Catholic Church by teaching that the Bible is the only source of divinely revealed knowledge and opposed sacerdotalism by considering all baptised Christians to be a holy priesthood. Those who identify with Luther's teachings are called Lutherans. His translation of the Bible into the language of the people (instead of Latin) made it more accessible, causing a tremendous impact on the church and on German culture. It fostered the development of a standard version of the German language, added several principles to the art of translation, and influenced the translation into English of the King James Bible. His hymns influenced the development of singing in churches. His marriage to Katharina von Bora set a model for the practice of clerical marriage, allowing Protestant priests to marry. In his later years, Luther became strongly anti-Judaic, writing that Jewish homes should be destroyed, their synagogues burned, money confiscated and liberty curtailed. These statements have made Luther a controversial figure among many historians and religious scholars.

Martin Luther was born to Hans Luder (or Ludher, later Luther) and his wife Margarethe (née Lindemann) on 10 November 1483 in Eisleben, Germany, then part of the Holy Roman Empire. He was baptized as a Catholic the next morning on the feast day of St. Martin of Tours. His family moved to Mansfeld in 1484, where his father was a leaseholder of copper mines and smelters and served as one of four citizen representatives on the local council. Martin Marty describes Luther's mother as a hard-working woman of "trading-class stock and middling means" and notes that Luther's enemies would later wrongly describe her as a whore and bath attendant. He had several brothers and sisters, and is known to have been close to one of them, Jacob. Hans Luther was ambitious for himself and his family, and he was determined to see Martin, his eldest son, become a lawyer. He sent Martin to Latin schools in Mansfeld, then Magdeburg in 1497, where he attended a school operated by a lay group called the Brethren of the Common Life, and Eisenach in 1498. The three schools focused on the so-called "trivium": grammar, rhetoric, and logic. Luther later compared his education there to purgatory and hell.

In 1501, at the age of nineteen, he entered the University of Erfurt — which he later described as a beerhouse and whorehouse. The schedule called for waking at four every morning for what has been described as "a day of rote learning and often wearying spiritual exercises." He received his master's degree in 1505. In accordance with his father's wishes, Luther enrolled in law school at the same university that year but dropped out almost immediately, believing that law represented uncertainty. Luther sought assurances about life and was drawn to theology and philosophy, expressing particular interest in Aristotle, William of Ockham, and Gabriel Biel. He was deeply influenced by two tutors, Bartholomäus Arnoldi von Usingen and Jodocus Trutfetter, who taught him to be suspicious of even the greatest thinkers and to test everything himself by experience. Philosophy proved to be unsatisfying, offering assurance about the use of reason but none about loving God, which to Luther was more important. Reason could not lead men to God, he felt, and he thereafter developed a love-hate relationship with Aristotle over the latter's emphasis on reason. For Luther, reason could be used to question men and institutions, but not God. Human beings could learn about God only through divine revelation, he believed, and Scripture therefore became increasingly important to him.

He later attributed his decision to an event: on 2 July 1505, he was on horseback during a thunderstorm and a lightning bolt struck near him as he was returning to university after a trip home. Later telling his father he was terrified of death and divine judgment, he cried out, "Help! Saint Anna, I will become a monk!" He came to view his cry for help as a vow he could never break. He left law school, sold his books, and entered a closed Augustinian friary in Erfurt on 17 July 1505. One friend blamed the decision on Luther's sadness over the deaths of two friends. Luther himself seemed saddened by the move. Those who attended a farewell supper walked him to the door of the Black Cloister. "This day you see me, and then, not ever again," he said. His father was furious over what he saw as a waste of Luther's education. Luther dedicated himself to monastic life, devoting himself to fasting, long hours in prayer, pilgrimage, and frequent confession. He would later remark, "If anyone could have gained heaven as a monk, then I would indeed have been among them." Luther described this period of his life as one of deep spiritual despair. He said, "I lost touch with Christ the Savior and Comforter, and made of him the jailor and hangman of my poor soul."

Johann von Staupitz, his superior, concluded that Luther needed more work to distract him from excessive introspection and ordered him to pursue an academic career. In 1507, he was ordained to the priesthood, and in 1508 began teaching theology at the University of Wittenberg. He received a Bachelor's degree in Biblical studies on 9 March 1508, and another Bachelor's degree in the Sentences by Peter Lombard in 1509. On 19 October 1512, he was awarded his Doctor of Theology and, on 21 October 1512, was received into the senate of the theological faculty of the University of Wittenberg, having been called to the position of Doctor in Bible. He spent the rest of his career in this position at the University of Wittenberg.

In 1516-17, Johann Tetzel, a Dominican friar and papal commissioner for indulgences, was sent to Germany by the Roman Catholic Church to sell indulgences to raise money to rebuild St Peter's Basilica in Rome. Roman Catholic theology stated that faith alone, whether fiduciary or dogmatic, cannot justify man; and that only such faith as is active in charity and good works (fides caritate formata) can justify man. The benefits of good works could be obtained by donating money to the church. On 31 October 1517, Luther wrote to Albrecht, Archbishop of Mainz and Magdeburg, protesting the sale of indulgences. He enclosed in his letter a copy of his "Disputation of Martin Luther on the Power and Efficacy of Indulgences," which came to be known as The 95 Theses. Hans Hillerbrand writes that Luther had no intention of confronting the church, but saw his disputation as a scholarly objection to church practices, and the tone of the writing is accordingly "searching, rather than doctrinaire." Hillerbrand writes that there is nevertheless an undercurrent of challenge in several of the theses, particularly in Thesis 86, which asks: "Why does the pope, whose wealth today is greater than the wealth of the richest Crassus, build the basilica of St. Peter with the money of poor believers rather than with his own money?" Luther objected to a saying attributed to Johann Tetzel that "As soon as the coin in the coffer rings, the soul from purgatory [also attested as 'into heaven'] springs." He insisted that, since forgiveness was God's alone to grant, those who claimed that indulgences absolved buyers from all punishments and granted them salvation were in error. Christians, he said, must not slacken in following Christ on account of such false assurances.

According to Philipp Melanchthon, writing in 1546, Luther "wrote theses on indulgences and posted them on the church of All Saints on 31 October 1517", an event now seen as sparking the Protestant Reformation. Some scholars have questioned Melanchthon's account, since he did not move to Wittenberg until a year later and no contemporaneous evidence exists for Luther's posting of the theses. Others counter that such evidence is unnecessary because it was the custom at the University of Wittenberg to advertise a disputation by posting theses on the door of All Saints' Church, also known as "Castle Church". The 95 Theses were quickly translated from Latin into German, printed, and widely copied, making the controversy one of the first in history to be aided by the printing press. Within two weeks, copies of the theses had spread throughout Germany; within two months throughout Europe. Luther's writings circulated widely, reaching France, England, and Italy as early as 1519. Students thronged to Wittenberg to hear Luther speak. He published a short commentary on Galatians and his Work on the Psalms. This early part of Luther's career was one of his most creative and productive. Three of his best-known works were published in 1520: To the Christian Nobility of the German Nation, On the Babylonian Captivity of the Church, and On the Freedom of a Christian.

From 1510 to 1520, Luther lectured on the Psalms, the books of Hebrews, Romans, and Galatians. As he studied these portions of the Bible, he came to view the use of terms such as penance and righteousness by the Roman Catholic Church in new ways. He became convinced that the church was corrupt in its ways and had lost sight of what he saw as several of the central truths of Christianity. The most important for Luther was the doctrine of justification – God's act of declaring a sinner righteous – by faith alone through God's grace. He began to teach that salvation or redemption is a gift of God's grace, attainable only through faith in Jesus as the Messiah. "This one and firm rock, which we call the doctrine of justification," he wrote, "is the chief article of the whole Christian doctrine, which comprehends the understanding of all godliness. Luther came to understand justification as entirely the work of God. This teaching by Luther was clearly expressed in his 1525 publication On the Bondage of the Will, which was written in response to On Free Will by Desiderius Erasmus (1524). Luther based his position on Predestination on St. Paul's epistle to the Ephesians 2:8-10. Against the teaching of his day that the righteous acts of believers are performed in cooperation with God, Luther wrote that Christians receive such righteousness entirely from outside themselves; that righteousness not only comes from Christ but actually is the righteousness of Christ, imputed to Christians (rather than infused into them) through faith. "That is why faith alone makes someone just and fulfills the law," he wrote. "Faith is that which brings the Holy Spirit through the merits of Christ." Faith, for Luther, was a gift from God.

Archbishop Albrecht of Mainz and Magdeburg did not reply to Luther's letter containing the 95 Theses. He had the theses checked for heresy and in December 1517 forwarded them to Rome. He needed the revenue from the indulgences to pay off a papal dispensation for his tenure of more than one bishopric. As Luther later noted, "the pope had a finger in the pie as well, because one half was to go to the building of St Peter's Church in Rome". Pope Leo X was used to reformers and heretics, and he responded slowly, "with great care as is proper." Over the next three years he deployed a series of papal theologians and envoys against Luther, which only served to harden the reformer's anti-papal theology. First, the Dominican theologian Sylvester Mazzolini drafted a heresy case against Luther, whom Leo then summoned to Rome. The Elector Frederick persuaded the pope to have Luther examined at Augsburg, where the Imperial Diet was held. There, in October 1518, Luther informed the papal legate Cardinal Cajetan that he did not consider the papacy part of the biblical Church, and the hearings degenerated into a shouting match. More than his writing the 95 Theses, Luther's confrontation of the church cast him as an enemy of the pope. Cajetan's original instructions had been to arrest Luther if he failed to recant, but he lacked the means in Augsburg, where the Elector guaranteed Luther's security. Luther slipped out of the city at night, without leave from Cajetan.

In January 1519, at Altenburg in Saxony, the papal nuncio Karl von Miltitz adopted a more conciliatory approach. Luther made certain concessions to the Saxon, who was a relative of the Elector, and promised to remain silent if his opponents did. The theologian Johann Maier von Eck, however, was determined to expose Luther's doctrine in a public forum. In June and July 1519 he staged a disputation with Luther's colleague Andreas Karlstadt at Leipzig and invited Luther to speak. Luther's boldest assertion in the debate was that Matthew 16:18 does not confer on popes the exclusive right to interpret scripture, and that therefore neither popes nor church councils were infallible. For this, Eck branded Luther a new Jan Hus, referring to the Czech reformer and heretic burned at the stake in 1415. From that moment, he devoted himself to Luther's defeat. On 15 June 1520, the Pope warned Luther with the papal bull (edict) Exsurge Domine that he risked excommunication unless he recanted 41 sentences drawn from his writings, including the 95 Theses, within 60 days. That autumn, Johann Eck proclaimed the bull in Meissen and other towns. Karl von Miltitz, a papal nuncio, attempted to broker a solution, but Luther, who had sent the Pope a copy of On the Freedom of a Christian in October, publicly set fire to the bull and decretals at Wittenberg on 10 December 1520, an act he defended in Why the Pope and his Recent Book are Burned and Assertions Concerning All Articles. As a consequence, Luther was excommunicated by Leo X on 3 January 1521, in the bull Decet Romanum Pontificem.

The enforcement of the ban on the 95 Theses fell to the secular authorities. On 18 April 1521, Luther appeared as ordered before the Diet of Worms. This was a general assembly of the estates of the Holy Roman Empire that took place in Worms, a town on the Rhine. It was conducted from 28 January to 25 May 1521, with Emperor Charles V presiding. Prince Frederick III, Elector of Saxony, obtained a safe conduct for Luther to and from the meeting. Johann Eck, speaking on behalf of the Empire as assistant of the Archbishop of Trier, presented Luther with copies of his writings laid out on a table and asked him if the books were his, and whether he stood by their contents. Luther confirmed he was their author, but requested time to think about the answer to the second question. He prayed, consulted friends, and gave his response the next day:

Unless I am convinced by the testimony of the Scriptures or by clear reason (for I do not trust either in the pope or in councils alone, since it is well known that they have often erred and contradicted themselves), I am bound by the Scriptures I have quoted and my conscience is captive to the Word of God. I cannot and will not recant anything, since it is neither safe nor right to go against conscience. May God help me. Amen.

Luther is sometimes also quoted as saying: "Here I stand. I can do no other". Recent scholars consider the evidence for these words to be unreliable, since they were inserted before "May God help me" only in later versions of the speech and not recorded in witness accounts of the proceedings. Over the next five days, private conferences were held to determine Luther's fate. The Emperor presented the final draft of the Diet of Worms on 25 May 1521, declaring Luther an outlaw, banning his literature, and requiring his arrest: "We want him to be apprehended and punished as a notorious heretic." It also made it a crime for anyone in Germany to give Luther food or shelter. It permitted anyone to kill Luther without legal consequence.

Luther's disappearance during his return trip was planned. Frederick III, Elector of Saxony had him intercepted on his way home by masked horsemen and escorted to the security of the Wartburg Castle at Eisenach. During his stay at Wartburg, which he referred to as "my Patmos", Luther translated the New Testament from Latin into German and poured out doctrinal and polemical writings. These included a renewed attack on Archbishop Albrecht of Mainz, whom he shamed into halting the sale of indulgences in his episcopates, and a "Refutation of the Argument of Latomus," in which he expounded the principle of justification to Jacobus Latomus, an orthodox theologian from Louvain. In this work, one of his most emphatic statements on faith, he argued that every good work designed to attract God's favour is a sin. All humans are sinners by nature, he explained, and God's grace, which cannot be earned, alone can make them just. On 1 August 1521, Luther wrote to Melanchthon on the same theme: "Be a sinner, and let your sins be strong, but let your trust in Christ be stronger, and rejoice in Christ who is the victor over sin, death, and the world. We will commit sins while we are here, for this life is not a place where justice resides."

In the summer of 1521, Luther widened his target from individual pieties like indulgences and pilgrimages to doctrines at the heart of Church practices. In On the Abrogation of the Private Mass, he condemned as idolatry the idea that the mass is a sacrifice, asserting instead that it is a gift, to be received with thanksgiving by the whole congregation. His essay On Confession, Whether the Pope has the Power to Require It rejected compulsory confession and encouraged private confession and absolution, since "every Christian is a confessor." In November, Luther wrote The Judgement of Martin Luther on Monastic Vows. He assured monks and nuns that they could break their vows without sin, because vows were an illegitimate and vain attempt to win salvation. Luther made his pronouncements from Wartburg in the context of rapid developments at Wittenberg, of which he was kept fully informed. Andreas Karlstadt, supported by the ex-Augustinian Gabriel Zwilling, embarked on a radical programme of reform there in June 1521, exceeding anything envisaged by Luther. The reforms provoked disturbances, including a revolt by the Augustinian monks against their prior, the smashing of statues and images in churches, and denunciations of the magistracy. After secretly visiting Wittenberg in early December 1521, Luther wrote A Sincere Admonition by Martin Luther to All Christians to Guard Against Insurrection and Rebellion. Wittenberg became even more volatile after Christmas when a band of visionary zealots, the so-called Zwickau prophets, arrived, preaching revolutionary doctrines such as the equality of man, adult baptism, and Christ'’s imminent return. When the town council asked Luther to return, he decided it was his duty to act.

Luther secretly returned to Wittenberg on 6 March 1522. "During my absence," he wrote to the Elector, "Satan has entered my sheepfold, and committed ravages which I cannot repair by writing, but only by my personal presence and living word." For eight days in Lent, beginning on Invocavit Sunday, 9 March, Luther preached eight sermons, which became known as the "Invocavit Sermons." In these sermons, he hammered home the primacy of core Christian values such as love, patience, charity, and freedom, and reminded the citizens to trust God's word rather than violence to bring about necessary change. The effect of Luther's intervention was immediate. After the sixth sermon, the Wittenberg jurist Jerome Schurf wrote to the elector: "Oh, what joy has Dr. Martin’s return spread among us! His words, through divine mercy, are bringing back every day misguided people into the way of the truth." Luther next set about reversing or modifying the new church practices. By working alongside the authorities to restore public order, he signalled his reinvention as a conservative force within the Reformation. After banishing the Zwickau prophets, he now faced a battle not only against the established Church but against radical reformers who threatened the new order by fomenting social unrest and violence. Despite his victory in Wittenberg, Luther was unable to stifle radicalism further afield. Preachers such as Zwickau prophet Nicholas Storch and Thomas Müntzer helped instigate the Peasants' War of 1524–25, during which many atrocities were committed, often in Luther's name. There had been revolts by the peasantry on a smaller scale since the 15th century. Luther's pamphlets against the Church and the hierarchy, often worded with "liberal" phraseology, now led many peasants to believe he would support an attack on the upper classes in general. Revolts broke out in Franconia, Swabia, and Thuringia in 1524, even drawing support from disaffected nobles, many of whom were in debt. Gaining momentum under the leadership of radicals such as Müntzer in Thuringia and Michael Gaismair in Tyrol, the revolts turned into war.

Luther sympathised with some of the peasants' grievances, as he showed in his response to the Twelve Articles of the Black Forest in May 1525, but he reminded the aggrieved to obey the temporal authorities. During a tour of Thuringia, he became enraged at the widespread burning of convents, monasteries, bishops’ palaces, and libraries. In Against the Murderous, Thieving Hordes of Peasants, written on his return to Wittenberg, he explained the Gospel teaching on wealth, condemned the violence as the devil's work, and called for the nobles to put down the rebels like mad dogs. Luther justified his opposition to the rebels on three grounds. First, in choosing violence over lawful submission to the secular government, they were ignoring Christ's counsel to "Render unto Caesar the things that are Caesar's"; St. Paul had written in his epistle to the Romans 13:1-7 that all authorities are appointed by God and therefore should not be resisted. This reference from the Bible forms the foundation for the doctrine known as the Divine Right of Kings, or, in the German case, the divine right of the princes. Second, the violent actions of rebelling, robbing, and plundering placed the peasants "outside the law of God and Empire," so they deserved "death in body and soul, if only as highwaymen and murderers." Lastly, Luther charged the rebels with blasphemy for calling themselves "Christian brethren" and committing their sinful acts under the banner of the Gospel. Without Luther's backing for the uprising, many rebels laid down their weapons; others felt betrayed. Their defeat by the Swabian League at the Battle of Frankenhausen on 15 May 1525, followed by Müntzer’s execution, brought the revolutionary stage of the Reformation to a close. Thereafter, radicalism found a refuge in the anabaptist movement and other sects, while Luther's Reformation flourished under the wing of the secular powers.

Martin Luther married Katharina von Bora, one of 12 nuns he had helped escape from the Nimbschen Cistercian convent in April 1523, when he arranged for them to be smuggled out in herring barrels. "Suddenly, and while I was occupied with far different thoughts," he wrote to Wenceslaus Link, "the Lord has plunged me into marriage." Katherina was 26 years old, Luther was 41 years old. On 13 June 1525, the couple was engaged with Johannes Bugenhagen, Justus Jonas, Johannes Apel, Philipp Melanchthon and Lucas Cranach the Elder and his wife as witnesses. On the evening of the same day, the couple was married by Bugenhagen. The ceremonial walk to the church and the wedding banquet were left out, and were made up two weeks later on 27 June. Some priests and former monks had already married, including Andreas Karlstadt and Justus Jonas, but Luther's wedding set the seal of approval on clerical marriage. He had long condemned vows of celibacy on Biblical grounds, but his decision to marry surprised many, not least Melanchthon, who called it reckless. Luther had written to George Spalatin on 30 November 1524, "I shall never take a wife, as I feel at present. Not that I am insensible to my flesh or sex (for I am neither wood nor stone); but my mind is averse to wedlock because I daily expect the death of a heretic." Before marrying, Luther had been living on the plainest food, and, as he admitted himself, his mildewed bed was not properly made for months at a time.

Luther and his wife moved into a former monastery, "The Black Cloister," a wedding present from the new elector John the Steadfast (1525–32). They embarked on what appeared to have been a happy and successful marriage, though money was often short. Between bearing six children, four of whom survived to adulthood, Katharina helped earn the couple a living by farming the land and taking in boarders. Luther confided to Michael Stiefel on 11 August 1526: "My Katie is in all things so obliging and pleasing to me that I would not exchange my poverty for the riches of Croesus."

By 1526, Luther found himself increasingly occupied in organising a new church. His Biblical ideal of congregations' choosing their own ministers had proved unworkable. According to Bainton: "Luther's dilemma was that he wanted both a confessional church based on personal faith and experience and a territorial church including all in a given locality. If he were forced to choose, he would take his stand with the masses, and this was the direction in which he moved." From 1525 to 1529, he established a supervisory church body, laid down a new form of worship service, and wrote a clear summary of the new faith in the form of two catechisms. To avoid confusing or upsetting the people, Luther avoided extreme change. He also did not wish to replace one controlling system with another. He concentrated on the church in the Electorate of Saxony, acting only as an adviser to churches in new territories, many of which followed his Saxon model. He worked closely with the new elector, John the Steadfast, to whom he turned for secular leadership and funds on behalf of a church largely shorn of its assets and income after the break with Rome. For Luther's biographer Martin Brecht, this partnership "was the beginning of a questionable and originally unintended development towards a church government under the temporal sovereign". The elector authorised a visitation of the church, a power formerly exercised by bishops. At times, Luther's practical reforms fell short of his earlier radical pronouncements. For example, the Instructions for the Visitors of Parish Pastors in Electoral Saxony (1528), drafted by Melanchthon with Luther's approval, stressed the role of repentance in the forgiveness of sins, despite Luther's position that faith alone ensures justification. The Eisleben reformer Johannes Agricola challenged this compromise, and Luther condemned him for teaching that faith is separate from works. The Instruction is a problematic document for those seeking a consistent evolution in Luther's thought and practice.

In response to demands for a German liturgy, Luther wrote a German Mass, which he published in early 1526. He did not intend it as a replacement for his 1523 adaptation of the Latin Mass but as an alternative for the "simple people", a "public stimulation for people to believe and become Christians." Luther based his order on the Catholic service but omitted "everything that smacks of sacrifice"; and the Mass became a celebration where everyone received the wine as well as the bread. He retained the elevation of the host and chalice, while trappings such as the Mass vestments, altar, and candles were made optional, allowing freedom of ceremony. Some reformers, including followers of Huldrych Zwingli, considered Luther's service too papistic; and modern scholars note the conservatism of his alternative to the Catholic mass. Luther's service, however, included congregational singing of hymns and psalms in German, as well as of parts of the liturgy, including Luther's unison setting of the Creed. To reach the simple people and the young, Luther incorporated religious instruction into the weekday services in the form of the catechism. He also provided simplified versions of the baptism and marriage services. Luther and his colleagues introduced the new order of worship during their visitation of Electoral Saxony, which began in 1527. They also assessed the standard of pastoral care and Christian education in the territory. "Merciful God, what misery I have seen," Luther wrote, "the common people knowing nothing at all of Christian doctrine ... and unfortunately many pastors are well-nigh unskilled and incapable of teaching."

Luther devised the catechism as a method of imparting the basics of Christianity to the congregations. In 1529, he wrote the Large Catechism, a manual for pastors and teachers, as well as a synopsis, the Small Catechism, to be memorised by the people themselves. The catechisms provide easy-to-understand instructional and devotional material on the Ten Commandments, the Apostles' Creed, the Lord's Prayer, baptism, and the Lord's Supper. Luther incorporated questions and answers in the catechism so that the basics of Christian faith would not just be learned by rote, "the way monkeys do it", but understood. The catechism is one of Luther's most personal works. "Regarding the plan to collect my writings in volumes," he wrote, "I am quite cool and not at all eager about it because, roused by a Saturnian hunger, I would rather see them all devoured. For I acknowledge none of them to be really a book of mine, except perhaps the Bondage of the Will and the Catechism." The Small Catechism has earned a reputation as a model of clear religious teaching. It remains in use today, along with Luther's hymns and his translation of the Bible. Luther's Small Catechism proved especially effective in helping parents teach their children; likewise the Larger Catechism was effective for pastors. Using the German vernacular they expressed the Apostles' Creed in simpler, more personal, Trinitarian language. He rewrote each article of the Creed to express the character of the Father, the Son, or the Holy Spirit. Luther's goal was to enable the catechumens to see themselves as a personal object of the work of the three persons of the Trinity, each of which works in the catechumen's life. That is, Luther depicts the Trinity not as a doctrine to be learned, but as persons to be known. The Father creates, the Son redeems, and the Spirit sanctifies, a divine unity with separate personalities. Salvation originates with the Father and draws the believer to the Father. Luther's treatment of the Apostles Creed must be understood in the context of the Decalogue (the Ten Commandments) and the Lord's Prayer, which are also part of the Lutheran catechical teaching.

Luther had published his German translation of the New Testament in 1522, and he and his collaborators completed the translation of the Old Testament in 1534, when the whole Bible was published. He continued to work on refining the translation until the end of his life. Others had translated the Bible into German, but Luther tailored his translation to his own doctrine. When he was criticised for inserting the word "alone" after "faith" in Romans 3:28, he replied: "It is my Testament and my translation, and it shall continue to be mine". The result was an evangelical Bible, suited to the emerging Lutheran church. Luther's translation used the variant of German spoken at the Saxon chancellery, intelligible to both northern and southern Germans. He intended his vigorous, direct language to make the Bible accessible to everyday Germans, "for we are removing impediments and difficulties so that other people may read it without hindrance." Published at a time of rising demand for German-language publications, Luther's version quickly became the most popular Bible translation. As such, it made a significant contribution to the evolution of the German language and literature. Furnished with notes and prefaces by Luther, and with woodcuts by Lucas Cranach which contained anti-papal imagery, it played a major role in the spread of Luther's doctrine throughout Germany. The Luther Bible influenced other vernacular translations, such as William Tyndale's English Bible, a precursor of the King James Bible.

Luther was a prolific hymn writer, authoring hymns such as "A Mighty Fortress is Our God." Luther opened the way for a bringing together of high art and folk music, of all classes, clergy and laity, men, women and children. His device for this linking was the singing of German hymns in connection with worship, the school, the home, and the public arena. Luther's 1524 creedal hymn "We All Believe in One True God" is a three-stanza confession of faith prefiguring Luther's 1529 three-part explanation of the Apostles' Creed in the Small Catechism. Luther's hymn, adapted and expanded from an earlier German creedal hymn, gained widespread use in vernacular Lutheran liturgies as early as 1525. Sixteenth-century Lutheran hymnals also included Wir Glauben All among the catechetical hymns, although 18th-century hymnals tended to label the hymn as trinitarian rather than catechetical, and 20th-century Lutherans rarely use the hymn because of the perceived difficulty of its tune. Luther's 1538 hymnic version of the Lord's Prayer, "Vater Unser in Himmelreich," corresponds exactly to Luther's explanation of the prayer in the Small Catechism, with one stanza for each of the seven prayer petitions, plus opening and closing stanzas; the hymn functioned both as a liturgical setting of the Lord's Prayer and as a means of examining candidates on specific catechism questions. The extant manuscript shows multiple revisions, demonstrating Luther's concern to clarify and strengthen the text and to provide an appropriately prayerful tune. Other 16th- and 20th-century versifications of the Lord's Prayer have adopted Luther's tune, although modern texts are considerably shorter. Luther wrote "Aus Tiefer Not Schrei ich zu Dir" [From depths of woe I cry to you] in 1523 as a hymnic version of Psalm 130 and sent it as a sample to encourage evangelical colleagues to write psalm-hymns for use in German worship. In 1524 Luther developed his original four-stanza psalm paraphrase into a five-stanza Reformation hymn that developed the theme of "grace alone" more fully. Because it expressed essential Reformation doctrine, this expanded version of "Aus Tiefer Not" was designated as a regular component of several regional Lutheran liturgies and was widely used at funerals, including Luther's own. Along with Erhart Hegenwalt's hymnic version of Psalm 51, Luther's expanded hymn was also adopted for use with the fifth part of Luther's catechism, concerning confession. Luther's 1540 hymn "Christ unser Herr zum Jordan Kam" [To Jordan came the Christ our Lord] reflects the structure and substance of his questions and answers concerning baptism in the Small Catechism. Luther adopted a preexisting Johann Walter tune associated with a hymnic setting of Psalm 67's prayer for grace; Wolf Heintz's four-part setting of the hymn was used to introduce the Lutheran Reformation in Halle in 1541. Preachers and composers of the 18th century, including J.S. Bach, used this rich hymn as a subject for their own work, although its objective baptismal theology was displaced by more subjective hymns under the influence of late-19th-century Lutheran pietism.

In October 1529, Philip I, Landgrave of Hesse convoked an assembly of German and Swiss theologians at the Marburg Colloquy, to establish doctrinal unity in the emerging Protestant states. Agreement was achieved on fourteen points out of fifteen, the exception being the nature of the Eucharist — the sacrament of the Lord's Supper — an issue crucial to Luther. The theologians, including Zwingli, Melanchthon, Martin Bucer, and Johannes Oecolampadius, differed on the significance of the words spoken by Jesus at the Last Supper: "This is my body which is for you," "This cup is the new covenant in my blood" (1 Corinthians 11:23–26). Luther insisted on the Real Presence of the body and blood of Christ in the consecrated bread and wine, which he called the sacramental union, while his opponents believed God to be only spiritually or symbolically present. Zwingli, for example, denied Jesus's ability to be in more than one place at a time; but Luther stressed his ubiquity. According to transcripts, the debate sometimes became confrontational. Citing Jesus's words "The flesh profiteth nothing" (John 6.63), Zwingli said, "This passage breaks your neck". "Don't be too proud," Luther retorted, "German necks don't break that easily. This is Hesse, not Switzerland." On his table Luther wrote the words "Hoc est corpus meum" ("This is my body") in chalk, to continually indicate his firm stance. Despite the disagreements on the Eucharist, the Marburg Colloquy paved the way for the signing in 1530 of the Augsburg Confession, and for the formation of the Schmalkaldic League the following year by leading Protestant nobles such as John of Saxony, Philip of Hesse, and Georg, Margrave of Brandenburg-Ansbach. The reformed Swiss cities, however, did not sign these agreements. Luther found himself leading a denomination within Protestantism rather than the movement as a whole. Interpretations of the Eucharist differ among Protestants to this day.

At the time of the Marburg Colloquy, Suleiman the Magnificent was besieging Vienna with a vast Ottoman army. Luther had argued against resisting the Turks in his 1518 Explanation of the Ninety-five Theses, provoking accusations of defeatism. He saw the Turks as ascourge sent to punish Christians by God, as agents of the biblical apocalypse that would destroy the antichrist, whom Luther believed to be the papacy, and the Roman Church. He consistently rejected the idea of a Holy War, "as though our people were an army of Christians against the Turks, who were enemies of Christ. This is absolutely contrary to Christ's doctrine and name". On the other hand, in keeping with his doctrine of the two kingdoms, Luther did support non-religious war against the Turks. In 1526, he argued in Whether Soldiers can be in a State of Grace that national defence is reason for a just war. By 1529, in On War against the Turk, he was actively urging Emperor Charles V and the German people to fight a secular war against the Turks. He made clear, however, that the spiritual war against an alien faith was separate, to be waged through prayer and repentance. Around the time of the Siege of Vienna, Luther wrote a prayer for national deliverance from the Turks, asking God to "give to our emperor perpetual victory over our enemies". In 1542, Luther read a Latin translation of the Qur'an. He went on to produce several critical pamphlets on the Islamic faith, which he called Mohammedanism or the Turk. Though Luther saw the Muslim faith as a tool of the devil, he was indifferent to its practice: "Let the Turk believe and live as he will, just as one lets the papacy and other false Christians live." He opposed banning the publication of the Qur'an, wanting it exposed to scrutiny.

Shaken by the Siege of Vienna, Charles V convened an Imperial Diet at Augsburg in 1530, aiming to unite the empire against the Turks. To achieve this, he needed first to resolve the religious controversies in his lands, "considering with love and kindness the views of everybody". He asked for a statement of the evangelical case, and one was duly devised by Luther, Melanchthon, and their Wittenberg colleagues. Melanchthon drafted the document, known as the Augsburg Confession, and travelled with the elector's party to Augsburg, where it was read to the emperor and diet on 25 June 1530. Luther was left behind at the Coburg fortress in southern Saxony because he remained under the imperial ban and lacked a safe-conduct to attend the diet. His writings during his 165 days at Coburg, including the Exhortation to all Clergy Assembled at Augsburg, show that, unlike Melanchthon, he was set against making concessions. Despite the Confession's avoidance of strident language or abuse of the pope, the diet rejected it on 22 September. The reformers were ordered to renounce heresy and submit to the control of the Catholic Church by the following April or face the imperial army. The decision confirmed Luther's belief that the mission had been futile. It prompted the Lutheran princes to form a military alliance, the Schmalkaldic League, which Luther cautiously supported on grounds of self-defence in his Warning to His Dear German People of 1531. The Augsburg Confession had become the statement of faith on which Lutherans were prepared to stand or fall. Though a modified version of Luther's position, it is regarded as the first Lutheran treatise.

From December 1539, Luther became implicated in the bigamy of Philip I, Landgrave of Hesse, who wanted to marry one of his wife's ladies-in-waiting. Philip solicited the approval of Luther, Melanchthon, and Bucer, citing as a precedent the polygamy of the patriarchs. The theologians were not prepared to make a general ruling, and they reluctantly advised the landgrave that if he was determined, he should marry secretly and keep quiet about the matter. As a result, on 4 March 1540, Philip married a second wife, Margarethe von der Sale, with Melanchthon and Bucer among the witnesses. However, Philip was unable to keep the marriage secret, and he threatened to make Luther's advice public. Luther told him to "tell a good, strong lie" and deny the marriage completely, which Philip did during the subsequent public controversy. In the view of Luther's biographer Martin Brecht, "giving confessional advice for Philip of Hesse was one of the worst mistakes Luther made, and, next to the landgrave himself, who was directly responsible for it, history chiefly holds Luther accountable". Brecht argues that Luther's mistake was not that he gave private pastoral advice, but that he miscalculated the political implications. The affair caused lasting damage to Luther's reputation.

Luther wrote about the Jews throughout his career, though only a few of his works dealt with them directly. Luther rarely encountered Jews during his life, but his attitudes reflected a theological and cultural tradition which saw Jews as a rejected people guilty of the murder of Christ, and he lived within a local community that had expelled Jews some ninety years earlier. He considered the Jews blasphemers and liars because they rejected the divinity of Jesus, whereas Christians believed Jesus was the Messiah. At the same time, Luther believed that all human beings who set themselves against God shared one and the same guilt. As early as 1516, Luther wrote, "…[M]any people are proud with marvelous stupidity when they call the Jews dogs, evildoers, or whatever they like, while they too, and equally, do not realize who or what they are in the sight of God". In 1523, Luther advised kindness toward the Jews in That Jesus Christ was Born a Jew, but only with the aim of converting them to Christianity. When his efforts at conversion failed, he grew increasingly bitter toward them. Luther's other major works on the Jews were his 60,000-word treatise Von den Juden und Ihren Lügen (On the Jews and Their Lies), and Vom Schem Hamphoras und vom Geschlecht Christi (On the Holy Name and the Lineage of Christ), both published in 1543, three years before his death. Luther argued that the Jews were no longer the chosen people but "the devil's people": he referred to them with violent, vile language. Luther advocated setting synagogues on fire, destroying Jewish prayerbooks, forbidding rabbis from preaching, seizing Jews' property and money, and smashing up their homes, so that these "poisonous envenomed worms" would be forced into labour or expelled "for all time". In Robert Michael's view, Luther's words "We are at fault in not slaying them" amounted to a sanction for murder. Luther spoke out against the Jews in Saxony, Brandenburg, and Silesia. Josel of Rosheim, the Jewish spokesman who tried to help the Jews of Saxony in 1537, later blamed their plight on "that priest whose name was Martin Luther — may his body and soul be bound up in hell! — who wrote and issued many heretical books in which he said that whoever would help the Jews was doomed to perdition." Josel asked the city of Strasbourg to forbid the sale of Luther's anti-Jewish works: they refused initially, but relented when a Lutheran pastor in Hochfelden used a sermon to urge his parishioners to murder Jews. Luther's influence persisted after his death. Throughout the 1580s, riots led to the expulsion of Jews from several German Lutheran states.

Luther was the most widely read author of his generation, and he acquired the status of a prophet within Germany. According to the prevailing view among historians, his anti-Jewish rhetoric contributed significantly to the development of antisemitism in Germany, and in the 1930s and 1940s provided an "ideal underpinning" for the National Socialists' attacks on Jews. Reinhold Lewin writes that "whoever wrote against the Jews for whatever reason believed he had the right to justify himself by triumphantly referring to Luther." According to Michael, just about every anti-Jewish book printed in the Third Reich contained references to and quotations from Luther. Heinrich Himmler wrote admiringly of his writings and sermons on the Jews in 1940. The city of Nuremberg presented a first edition of On the Jews and their Lies to Julius Streicher, editor of the Nazi newspaper Der Stürmer, on his birthday in 1937; the newspaper described it as the most radically anti-Semitic tract ever published. On 17 December 1941, seven Protestant regional church confederations issued a statement agreeing with the policy of forcing Jews to wear the yellow badge, "since after his bitter experience Luther had already suggested preventive measures against the Jews and their expulsion from German territory." According to Daniel Goldhagen, Bishop Martin Sasse, a leading Protestant churchman, published a compendium of Luther's writings shortly after Kristallnacht, for which Diarmaid MacCulloch, Professor of the History of the Church in the University of Oxford argued that Luther's writing was a "blueprint." Sasse applauded the burning of the synagogues and the coincidence of the day, writing in the introduction, "On November 10, 1938, on Luther's birthday, the synagogues are burning in Germany." The German people, he urged, ought to heed these words "of the greatest antisemite of his time, the warner of his people against the Jews." According to Professor Dick Geary, the Nazis won a larger share of the vote in Protestant than in Catholic areas of Germany in elections of 1928 to November 1932.

At the heart of scholars' debate about Luther's influence is whether it is anachronistic to view his work as a precursor of the racial antisemitism of the National Socialists. Some scholars see Luther's influence as limited, and the Nazis' use of his work as opportunistic. Biographer Martin Brecht points out that "There is a world of difference between his belief in salvation and a racial ideology. Nevertheless, his misguided agitation had the evil result that Luther fatefully became one of the 'church fathers' of anti-Semitism and thus provided material for the modern hatred of the Jews, cloaking it with the authority of the Reformer." Johannes Wallmann argues that Luther's writings against the Jews were largely ignored in the 18th and 19th centuries, and that there was no continuity between Luther's thought and Nazi ideology. Uwe Siemon-Netto agreed, arguing that it was because the Nazis were already anti-Semites that they revived Luther's work. Hans J. Hillerbrand agreed that to focus on Luther was to adopt an essentially ahistorical perspective of Nazi antisemitism that ignored other contributory factors in German history. Similarly, Roland Bainton, noted church historian and Luther biographer, wrote "One could wish that Luther had died before ever this tract was written. His position was entirely religious and in no respect racial." Other scholars argue that, even if his views were merely anti-Judaic, their violence lent a new element to the standard Christian suspicion of Judaism. Ronald Berger writes that Luther is credited with "Germanizing the Christian critique of Judaism and establishing anti-Semitism as a key element of German culture and national identity." Paul Rose argues that he caused a "hysterical and demonizing mentality" about Jews to enter German thought and discourse, a mentality that might otherwise have been absent. Since the 1980s, Lutheran Church denominations have repudiated Martin Luther's statements against the Jews and have rejected the use of them to incite hatred against Lutherans.

Luther had been suffering from ill health for years, including Ménière's disease, vertigo, fainting, tinnitus, and a cataract in one eye. From 1531 to 1546, his health deteriorated further. The years of struggle with Rome, the antagonisms with and among his fellow reformers, and the scandal which ensued from the bigamy of the Philip of Hesse incident, in which Luther had played a leading role, all may have contributed. In 1536, he began to suffer from kidney and bladder stones, and arthritis, and an ear infection ruptured an ear drum. In December 1544, he began to feel the effects of angina. His poor physical health made him short-tempered and even harsher in his writings and comments. His wife Katharina was overheard saying, "Dear husband, you are too rude," and he responded, "They are teaching me to be rude." His last sermon was delivered at Eisleben, his place of birth, on 15 February 1546, three days before his death. It was "entirely devoted to the obdurate Jews, whom it was a matter of great urgency to expel from all German territory," according to Léon Poliakov. James Mackinnon writes that it concluded with a "fiery summons to drive the Jews bag and baggage from their midst, unless they desisted from their calumny and their usury and became Christians." Luther said, "we want to practice Christian love toward them and pray that they convert," but also that they are "our public enemies ... and if they could kill us all, they would gladly do so. And so often they do."

Luther's final journey, to Mansfeld, was taken because of his concern for his siblings' families continuing in their father Hans Luther's copper mining trade. Their livelihood was threatened by Count Albrecht of Mansfeld bringing the industry under his own control. The controversy that ensued involved all four Mansfeld counts: Albrecht, Philip, John George, and Gerhard. Luther journeyed to Mansfeld twice in late 1545 to participate in the negotiations for a settlement, and a third visit was needed in early 1546 for their completion. The negotiations were successfully concluded on 17 February 1546. After 8:00 p.m., he experienced chest pains. When he went to his bed, he prayed, "Into your hand I commit my spirit; you have redeemed me, O Lord, faithful God" (Ps. 31:5), the common prayer of the dying. At 1:00 a.m. he awoke with more chest pain and was warmed with hot towels. He thanked God for revealing his Son to him in whom he had believed. His companions, Justus Jonas and Michael Coelius, shouted loudly, "Reverend father, are you ready to die trusting in your Lord Jesus Christ and to confess the doctrine which you have taught in his name?" A distinct "Yes" was Luther's reply. An apoplectic stroke deprived him of his speech, and he died shortly afterwards at 2:45 a.m. on 18 February 1546, aged 62, in Eisleben, the city of his birth. He was buried in the Castle Church in Wittenberg, beneath the pulpit. The funeral was held by his friends Johannes Bugenhagen and Philipp Melanchthon. A year later, troops of Luther's adversary Charles V, Holy Roman Emperor entered the town, but were ordered by Charles not to disturb the grave.