The people in Judea that did not accept Christ and his followers had to flee when Rome destroyed Jerusalem and banished them permanently. They fled to Babylon and regrouped. Without their ancestral lands or the temple that was so central to their religion, and with all of the honest people becoming Christian, they had to wage war against Christianity to have any hope of surviving. That's where the Talmud came from. Their entire religion is based on "how do we destroy Christianity?"