I saw a rabbi on the Discovery channel who claimed that many aspects of the Christian and Jewish texts contain parables that stem from a conglomerate of pagan religions/traditions in the surrounding regions - just sanitized and restructured to fit the new religions. Also, during the conversion of Rome, many Christian holidays just happen to be celebrated on pre-existing mythological holidays which made it easier for conversion purposes. Easter, for instance, was a fertility festival which centered around the fertility god Esther and which used rabbits and eggs in the ceremony as signs of fertility. I would find a link but I'm too lazy right now.
