• Judge of the Areopagus Dionysius the Areopagite, 1st Century
• Theologian and Philosopher Pseudo - Dionysius the Areopagite, 5th Century

As related in the Acts of the Apostles (Acts 17:34), he was converted to Christianity by the preaching of Paul the Apostle, being first stirred to Christian doctrine by Paul's sermon at the Areopagus:

Howbeit certain men clave unto him, and believed: among the which was Dionysius the Areopagite, and a woman named Damaris, and others with them.

After his conversion, Dionysius became the first Bishop of Athens, though he is sometimes counted as the second after Hierotheus. He is venerated as a saint in the Catholic and the Eastern Orthodox churches. He is the patron saint of Athens and is venerated as the protector of judges and the judiciary. His memory is celebrated on October 3.

In the early sixth century the so-called Corpus Dionysiacum, a series of writings of a mystical nature, employing Neoplatonic language to elucidate Christian theological and mystical ideas, was ascribed to the Areopagite. Its author is now known as Pseudo-Dionysius the Areopagite. A minority of scholars argue in favor of authenticity citing internal historical details and the existence of explicit citations of Dionysius predating Proclus by writers such as Dionysius of Alexandria and Gregory Nazianzus. Even Proclus himself appears to cite an external authority for a euphemism ("flowers and supersubstantial lights") when the said verbiage is found explicitly in the Corpus Dionysiacum.

Dionysius has been misidentified with the martyr Dionysius, the first Bishop of Paris. However, this mistake by a ninth century writer is ignored and each saint is commemorated on his respective day.

In Athens there are two large churches bearing his name, one in Kolonaki on Skoufa Street, while the other is the Catholic Metropolis of Athens, on Panepistimiou Street. The pedestrian walkway around the Acropolis, which passes through the rock of the Areios Pagos, also bears his name.

Dionysius is the patron saint of the Gargaliani of Messenia, as well as in the village of Dionysi in the south of the prefecture of Heraklion. The village was named after him and is the only village of Crete with a church in honor of Saint Dionysios Areopagitis.

His works are mystical and show strong Neoplatonic influence. For example he uses Plotinus' well known analogy of a sculptor cutting away that which does not enhance the desired image. He shows familiarity with Proclus, which indicates he wrote no earlier than the 5th century, as well as influence from Saint Clement of Alexandria, the Cappadocian Fathers, Origen of Alexandria and others. The liturgical references in his writings also date his works after the 4th century. His writings were first cited in 519 in a work by Severus of Antioch, Adversus apologiam Juliani, who cited the Fourth Letter. Debates over the author of the Dionysian corpus began in the Renaissance.

There is a distinct difference between pagan Neoplatonism and that of Eastern Christianity. In the former all life returns to the source to be stripped of individual identity, a process called henosis, while in orthodox Christianity the Likeness of God in man is restored by grace (by being united to God the Holy Trinity through participation in His divine energies), a process called theosis.

Dionysos appears to have belonged to the group which attempted a compromise between monophysitism and orthodox teaching. His thought was initially used by monophysites to back up parts of their arguments but his writings were eventually adopted by other church theologians, primarily due to the work of John of Scythopolis and Maximus the Confessor in producing an orthodox interpretation.

The Dionysian writings and their mystical teaching were universally accepted throughout the East, among both Chalcedonians and non-Chalcedonians. St. Gregory Palamas, for example, in referring to these writings, calls the author, "an unerring beholder of divine things". In the West the manuscripts became popular among theologians, particularly through the medium of John Scotus Eriugena. Thomas Aquinas cites Pseudo - Dionysius over 1700 times. Dionysius' portrayal of the "via negativa" was particularly influential among contemplatives and mystical theologians.

During the medieval period Saint Dionysius the Areopagite and Saint Denis of Paris were considered to be the same "Dionysius" who had been converted by Saint Paul in Acts 17:34. Medieval tradition held that Saint Dionysius the Areopagite had traveled to Rome and then was commissioned by the Pope to preach in Gaul (France), where he was martyred. This confusion of historical detail was compounded by the common acceptance of Pseudo - Dionysius's writings as the authentic work of the Biblical Dionysius of Acts 17:34. The great Abbey of Saint - Denis just north of Paris claimed to have the relics of Dionysius. Around 1121, Pierre Abélard, a Benedictine monk at Saint Denis Basilica, turned his attention to the story of their patron saint, and disentangled the three different Dionysiuses. The monks were offended at the apparent demotion of Saint Denis, and Abélard did not remain long at Saint Denis. The confusion over the text might stem from the text being an oral tradition (declamatio) that was only at a later date finally put to record. According to the Stanford Encyclopedia of Philosophy "It must also be recognized that 'forgery' is a modern notion. Like Plotinus and the Cappadocian Fathers before him, Dionysius does not claim to be an innovator, but rather a communicator of a tradition."

The monastery of St. Denis, which had inadvertently conflated the two Dionysiuses, had a good Greek edition of Pseudo - Dionysius's works given to them by Charles the Bald, which was translated into Latin by John Scotus Eriugena in the late 9th century. This translation widely popularized both Pseudo - Dionysius' teaching and his explanation of the angels.

On pages 190 and 191 of Owen Gingerich's monograph on Copernicus The Book Nobody Read, reference is made to an astronomical fresco in the main gallery of the Escorial Library, near Madrid, Spain, built 1567-84, which shows Dionysius the Areopagite observing an eclipse at the time of Christ's crucifixion. In a footnote Gingerich mentions that an eclipse (of the sun by the moon) could not have happened at that time because Passover is a full moon event, and solar eclipses always happen at new moon.

The legend is based on a claim made by Pseudo - Dionysius in a letter addressed to Polycarp: "What have you to say about the solar eclipse which occurred when the Savior was put on the cross? At the time the two of us were in Heliopolis and we both witnessed the extraordinary phenomenon of the moon hiding the sun at the time that was out of season for their coming together... We saw the moon begin to hide the sun from the east, travel across to the other side of the sun, and return on its path so that the hiding and the restoration of the light did not take place in the same direction but rather in diametrically opposite directions..."

Pseudo - Dionysius had apparently read the Alexandrinus variant of Gospel of Luke (Luke 23:44-45) where the darkness said to have accompanied the crucifixion is attributed to an eclipse.

In 1457 the Italian humanist Lorenzo Valla wrote: "...the claim of 'Dionysius'... that he observed the eclipse of the sun at the hour of the Savior's death... is as blatant a fiction as the epistolary form of the report."

The authorship of the Dionysian Corpus was initially disputed; Severus and his party affirmed its apostolic dating, largely because it seemed to agree with their Christology. However, this dating was disputed by Hypatius of Ephesus, who met the monophysite party during the 532 meeting with Emperor Justinian I; Hypatius denied its authenticity on the grounds that none of the Fathers or Councils ever cited or referred to it. Hypatius condemned it along with the Apollinarian texts, distributed during the Nestorian controversy under the names of Pope Julius and Athanasius, which the monophysites entered as evidence supporting their position.

The first defense of its authenticity is undertaken by John of Scythopolis, whose commentary, the Scholia (ca. 540), on the Dionysian Corpus constitutes the first defense of its apostolic dating, wherein he specifically argues that the work is neither Apollinarian nor a forgery, probably in response both to monophysites and Hypatius — although even he, given his unattributed citations of Plotinus in interpreting Dionysius, might have known better. Dionysius' authenticity is criticized later in the century, and defended by Theodore of Raithu; and by the 7th century, it is taken as demonstrated, affirmed by both Maximus the Confessor and the 649 Lateran Council. From that point forward, the authorship is largely not in question until the Renaissance.

The Florentine humanist Lorenzo Valla (d. 1457), in his commentaries on the New Testament, did much to establish that the author of the Corpus Areopagiticum could not have been St. Paul's convert, though he was unable to identify the actual historical author. The fictitious literary persona had long been accepted on face value by all its readers, with a couple of exceptions such as Nicholas of Cusa noted by modern historians, but whose reservations went unheard.

William Grocyn pursued Valla's lines of text criticism, and Valla's critical viewpoint of the authorship of the highly influential Corpus was accepted and publicized by Erasmus from 1504 onward, for which he was criticized by Catholic theologians. In the Leipzig disputation with Martin Luther, 1519, Johann Eck used the Corpus, specifically the Angelic Hierarchy, as argument for the apostolic origin of papal supremacy, pressing the Platonist analogy, "as above, so below".

During the 19th century modernist Catholics too came generally to accept that the author must have lived after the time of Proclus. Dionysius' identity is still disputed. The compilers of the Stanford Encyclopedia of Philosophy find pseudo - Dionysius to be most probably "a pupil of Proclus, perhaps of Syrian origin, who knew enough of Platonism and the Christian tradition to transform them both. Since Proclus died in 485, and since the first clear citation of Dionysius' works is by Severus of Antioch between 518 and 528, then we can place Dionysius' authorship between 485 and 518 - 28." Ronald Hathaway provides a table listing most of the major identifications of Dionysius: e.g., Ammonius Saccas, Dionysius the Great, Peter the Fuller, Dionysius the Scholastic, Severus of Antioch, Sergius of Reshaina, unnamed Christian followers of everyone from Origen of Alexandria to Basil of Caesarea, Eutyches to Proclus. Georgian academician Shalva Nutsubidze and Belgian professor Ernest Honigmann were authors of a theory identifying pseudo - Dionysius the Areopagite with Peter the Iberian. A more recent identification is with Damascius, the last scholarch of the School of Athens. There is no scholarly consensus on the question of Pseudo - Dionysius' identification.