The doctrine of incarnation—that God the Son took flesh and became man—is the central point of Christian theology. It is attested in the New Testament (John 1:14; 1 Tim. 3:16). During the fourth century there was a great debate about the incarnation of Christ, especially after the Arian heresy.
The Nicene Creed (325 a.d.) was composed in order to combat this heresy and states precisely, “We believe in one Lord Jesus Christ, . . . who for us men and for our salvation came down from heaven; he was incarnate of the Holy Spirit and of the Virgin Mary; and he became man.” The apostolic fathers of the Church, such as Ignatius of Antioch in his epistle to the Ephesians, studied this dogma.
One of the masterpieces of the Christian theological books is the work of Athanasius of Alexandria: On the Incarnation of the Word. This theme was also treated by Cyril of Alexandria and by Severus of Antioch, the great Church theologian. This dogma could be summarized in the beautiful hymn attributed to him:
O only begotten Son and Word of God, immortal and everlasting, accepting everything for our salvation; the incarnated from the Mother of God, the ever Virgin Mary; without change, Christ God, becoming man and crucified; through death, trode on death, One of the Holy Trinity, glorified with the Father and the Holy Spirit, save us.