When I was in Houston, Texas in 2000, I bought book by John Shelby Spong (who was bishop of Newark at the time) called Liberating the Gospels. It was such a radical re-imagining of the gospels, what they might have meant, and how seriously we should take them, that it pretty much turned me super-atheist instead of just the regular atheist I was up to that point. Or maybe it was being surrounded by Southern Baptists for two weeks. Highly recommended (the book, not Houston).
He offers a compelling view of the Gospels as thoroughly Jewish tests and powerfully argues that many of the key Gospel accounts of events in the life of Jesus are not literally true. He claims that the Gospels are a collection of Jewish midrashic stories written to convey the significance of Jesus, and is perhaps ironic that it was not Richard Dawkins or Daniel Dennett or Bertrand Russell who pushed me over the edge, but an episcopalian bishop.