Saint Paul was a sinner. He never met Jesus, but he experienced the famous conversion on the road to Damascus long after the Messiah had been crucified. Paul believed his Damascus experience had healed his guilty soul, but Jesus' own brother doubted Paul's tale.
James' rejection spurred Paul to hike the Roman highways of the Mediterranean world to proclaim the truth of Damascus, over and over again, if not for James' approval, then for his own. Had he not been healed at Damascus? And then there was the stinging thorn in his flesh that kept the guilty wound on his soul festering.
