Within
Christology, two specific theological concepts have emerged throughout history, in reference to the
Person of Christ: • monoprosopic concept (in Christology) advocates that Christ has only one person; • dyoprosopic concept (in Christology) advocates that Christ has two persons (divine and human). During the first half of the 5th century, some
Antiochene theologians, including
Theodore of Mopsuestia, and his disciple
Nestorius, questioned the concept of
hypostatic union of the two
natures (divine and human) of Jesus, but accepted a more loosely defined concept of the
prosopic union. Since their views on hypostatic union were seen as controversial, additional questions arose regarding their teachings on the prosopic union. Theodore believed that
incarnation of Jesus represents an indwelling of God different from the indwelling experienced by the
Old Testament prophets or
New Testament apostles. Jesus was viewed as a human being who shared the divine sonship of the Logos; the Logos united itself to Jesus from the moment of Jesus' conception. After the
resurrection, the human Jesus and the Logos reveal that they have always been one prosopon. Theodore addresses the prosopic union in applying prosopon to Christ the
Logos. He accounts for two expressions of Christ – human and divine. Yet, he does not mean Christ achieved a unity of the two expressions through the formation of a third prosopon, but that one prosopon is produced by the Logos giving his own countenance to the assured man. He interprets the unity of God and man in Christ along the lines of the body-
soul unity. Prosopon plays a special part in his interpretation of Christ. He rejected the Hypostasis concept – believing it to be a contradiction of Christ's true nature. He espoused that, in Christ, both body and soul had to be assumed. Christ assumed a soul and by the grace of God brought it to
immutability and to a full dominion over the sufferings of the body. Nestorius furthered Theodore's views on the prosopic union, claiming that prosopon is the "appearance" of the
ousia (essence), and stating: "the prosopon makes known the ousia". On several instances, he emphasized the relation of each of the two natures (divine and human) with their respective appearances, using the term prosopon both in plural forms, and also as a singular designation for the prosopic union. Such terminological complexities and inconsistencies proved to be challenging not only for his contemporary critiques or followers, but also for later commentators and scholars. The very suggestion of prosopic duality was challenging enough to cause heated debates among Christian theologians in the first half of the 5th century, resulting in official condemnation of such views. The
Council of Ephesus of 431 affirmed the teaching of "One Person" of Jesus Christ, condemning all other teachings. The
Council of Chalcedon in 451 reaffirmed the notion of One Person of Jesus Christ, formulating the famous
Chalcedonian Definition with its "
monoprosopic" (having one person) clauses, and in the same time explicitly denying the validity of "dyoprosopic" (having two persons) views. ==In Mandaeism==