Who was Paul the Apostle?

Paul (originally Saul) was a Pharisee who persecuted Christians until encountering the risen Christ on the Damascus road. He became the greatest missionary, planting churches throughout the Roman Empire and writing 13 New Testament letters. His theology of grace shapes Christian understanding to this day.

Why this answer? It starts with Galatians 2:20, then cross-checks Acts 9:1-19 and Philippians 3:4-11 so the summary stays anchored in Scripture.