The Gospel according to Mark opens with a clear statement about the identity of Jesus Christ as the Son of God (Mark 1:1). But another character also appears in the Gospels, referred to as the “Son of Man,” who does not seem to be identified with the Son of God himself. In fact, Jesus often speaks of him in the third person singular, as if he were someone distinct from himself: “He then began to teach them that the Son of Man must suffer many things” (Mark 8:31); “Jesus gave them orders not to tell anyone what they had seen until the Son of Man had risen from the dead” (Mark 9:9; cf. 9:12; 10:33); “At that time people will see the Son of Man coming in clouds with great power and glory” (Mark 13:26; cf. 14:62). Thus the question arises: are Jesus Christ, the Son of God and the Son of Man the same and identical person?
The issue of the uniqueness of the person of Christ arose from the very beginnings of Christian reflection, which saw, on the one hand, the great divine names or epithets that the New Testament attributes to him (Word, Son of God, Only Begotten, Wisdom, Power, and so on) and, on the other hand, his human side, revealed by the Gospels: hunger, thirst, sadness, “fear and anguish” (Mark 14:33). The question then arose as to how can all these different conditions be applied to a single subject? How can the Logos (Verbum) and the sarx (flesh = man) form truly, and not just accidentally, “one being”? How can we avoid the scandal of the cross for the Son of God if there is only one subject? We are facing something paradoxical, not explicable by anthropological categories. The problem is not only ancient, but also current, just as the question of Christ is always current.