Why do people become angry when someone mocks their religion?
People become angry when their religion is mocked because that religion is their whole life, their identity, and their hierarchy. As with Saul, who hated Jesus as an imposter destroying Judaism, any snide remark against what they love deeply naturally raises their ire; it is human nature.
Les explains that Saul of Tarsus was totally religious, an absolute believer of the Old Testament, a Pharisee of the Pharisees, of the tribe of Benjamin, a Jew through and through. He hated Jesus of Nazareth with a passion because he saw Him as an imposter trying to destroy the Mosaic Law and Judaism, which was his whole life. Les points out that people today are no different: if they love their particular religion, their hierarchy, or have a personal interest in someone at the top, they will not tolerate snide remarks without their ire being raised. That is just human nature. Saul felt Jesus was destroying the very bulwarks of Judaism, so he persecuted in the name of religion to do God a favor.