Wow. That's not a case for the "for the intellectual credibility of Christianity" - that's a bizarre truth claim about the four canonical gospels that appears to be based on ignorance of the historical provenance of the same and of the history of interpretation of the gospels. I would suggest a reading of people like John Dominic Crossan, Bruce Chilton, E.P sanders, John Gager, Marcus Borg and many many others before putting pen to paper next time Tim.
edit: there were literally hundreds of people in Galilee and Jersualam in the first century eh Tim?