John testified, saying, "I have seen the Spirit descending like a dove out of heaven, and it remained on him.
Without the witness of this Gospel, people might never have known how John the Baptist arrived at the conviction that Jesus was indeed the Christ. The apostle John, one of the great herald's disciples at first, was enlightened on this by John himself, and was, moreover, an eye-witness of the fulfillment of the key prophecy of identification.