Was Saul of Tarsus a sinner even though he was a religious zealot?
Yes. Although Saul of Tarsus was a religious man and a zealot of Judaism, God had to tell him that he was a sinner; he was undone. Religious zeal does not erase sin, and every person must believe to appropriate God's accomplished reconciliation.
Les explains that even though Saul of Tarsus was a religious man and a religious zealot of Judaism, God still had to tell him that he was a sinner and that he was undone. The context stresses that reconciliation has been accomplished for every person, and all they have to do is believe it to appropriate it. Therefore, religious sincerity or zeal is not the same as salvation; God has made the way simple so that lost humanity can come back to Himself, and He will have every right to judge the world.
For if the truth of God hath more abounded through my lie unto his glory; why yet am I also judged as a sinner?