Why did Saul persecute those who followed Jesus before his conversion?

Les explains that Saul was a religious zealot who honestly thought that by stamping out anything that referred to Jesus of Nazareth in Israel, he was doing the God of Abraham a service. But God suddenly stopped the man in his tracks, and Saul was saved on the road to Damascus. While Saul was still making his way into Damascus, now blind, the Lord spoke to Ananias, telling him to go into the street called Straight and inquire at the house of Judas for Saul of Tarsus, for behold, he prayeth. Ananias was to understand that Saul was being made ready for something special. Later, as Paul, he became a bondslave and prisoner of Christ for the distinct purpose of bringing pagan Gentiles out of their sin and spiritual darkness and into the knowledge of his gospel.