I've never been particularly impressed with Ehrman's arguments on the matter, and frankly I'm not particularly interested in the book because, well, I don't see the point of it. Obviously what matters is whether Jesus existed as he is described in the Gospels, which even Ehrman would argue (and has argued) he did not. Anything beyond that seems pretty masturbatory.
In any case, Carrier mentioned something kind of cool, that I never knew about. Here's the quote:
Paul in his own letters frequently talks about revelation as a source of Jesus’ teachings. Again, Ehrman even agrees that some of the teachings of Jesus were probably “learned” that way. But if some, why not all? Paul never once mentions any other source (except scripture: Romans 16:15-26; e.g. Hebrews 10:5-7 records a saying of Christ, which is in fact simply Psalms 40:6-7, so evidently Christians were also learning the “teachings” of Jesus by reading them as hidden messages in scripture).
I looked up those scriptures, and here they are:
6 Sacrifice and offering you did not desire – but my ears you have opened – burnt offerings and sin offerings you did not require. 7 Then I said, “Here I am, I have come—it is written about me in the scroll. [Psalm 40]
5 Therefore, when Christ came into the world, he said: “Sacrifice and offering you did not desire, but a body you prepared for me; 6 with burnt offerings and sin offerings you were not pleased. 7 Then I said, ‘Here I am – it is written about me in the scroll – I have come to do your will, my God.’” [Hebrews 10]
Like we needed more proof that the Bible is ordinary human fiction.