Juan 1:6

There came a man, sent from God, whose name was John.

The apostle John nowhere referred to the great herald as John the Baptist, but simply as John, as should have been expected, since the apostle himself was the only other John of Biblical significance in that entire era, thus supporting the conviction of apostolic authorship of this Gospel, and demanding the inference that the other John was the writer of this Gospel. Any forger would have been careful to explain which John he meant; but the apostle John had no need to do so.

Sent from God ... identifies John the Baptist as a true prophet with a valid message from God. This verse, and the two following, form a parenthesis in this prologue dealing with the mission of John the Baptist.