Not for purposes of this discussion, which is concerned only with the existence (or not) of Nazareth.
As for John's Gospel itself -- well, I have to admit it's my least favorite. It reminds me too much of Thucydides, who created speeches for people based on what they "would have said."
Jesus's speeches just don't read like they would have been spoken. I don't think John actually made anything up -- I think he worked awfully hard to write down Jesus' sayings as he remembered them from a long time earlier, and his personal writing style (and nascent theology, in all probability) got in the way.
Have you heard that John is a Gnostic Gospel?The allegation that the fourth gospel is a gnostic text dates as far back as the second century, yet it is part of the first known canon in the West -- the Muratorian fragment or canon, which dates from around the year 180 or 190 (author unknown).
The strongest evidence we have concerning the apostolic authority of the fourth gospel is the word of Irenaeus, bishop of Lyons (d. ca. 200), student of Polycarp, who in turn was a disciple of John.