Why did St. Paul change his beliefs?

He encountered Jesus Christ, whom he was persecuting on the road to Damasus. The account is recorded in the Book of Acts, Chapter 10. He was told by Jesus to meet a man named Ananias, and told Ananias to meet Saul. Ananias introduced him to the very hesitant disciples, who then taught him in the Way. His encounter with Christ was a profound, terrifying and mystical experience.