The prologue sets the earthly ministry of Jesus against a cosmic background and so gives us the theological key for understanding it. John begins, not at the baptism of Jesus as does Mark, nor even with his conception and birth as do Matthew and Luke, but “in the beginning” (v. 1), a phrase reminiscent of Ge 1:1. In this passage Jesus is identified as the incarnation of the eternal Word. On the rich background and significance of this term, see the commentaries (Barrett, 152-55; Beasley-Murray, 6-10).
This Word is brought into relationship with God in the closest possible way. He both was God and was present with God in the beginning (vv. 1-2). He was God's agent in creation (v. 3; cf. v. 10) and was the uncomprehended source of the life that was light for humankind (vv. 4-5). He brought salvation into his world (vv. 9-13), but, despite John's testimony (vv. 6-8), he was not universally received. It is this Word who became incarnate in Jesus (v. 14). John the Baptist gave testimony to his greatness (v. 15; cf. vv. 27, 30), and the author adds to John's testimony that Jesus superseded even Moses. Moses gave only the Law, but the Incarnate One gave grace and truth and revealed God the Father, whom no human has ever seen (vv. 16-18).
With this beginning, the author makes it clear that the story of Jesus is no mere earthly story about a merely human figure. Jesus is the incarnation of a divine person present with God before creation and identified with him. This must be kept firmly in mind as one reads the account that follows. In addition, the author sounds several themes that will recur throughout the gospel: life, the opposition of light and darkness, the world, belief and spiritual birth, truth, glory, and Father and (by implication) Son. For a brief but helpful summary of some of the characteristic ideas in John, see Turner (26-43).