1 Corinthians 15:9
For I am the least of the apostles, that am not meet to be called an apostle, because I persecuted the church of God. For I am the least of the apostles, that am not meet to be called an apostle, because I persecuted the church of God.
Long after his conversion Paul's settled judgment of himself was that he was the least of the apostles and unfit to be called an apostle because he had persecuted the church of God. His earlier unbelief gave him no moral right to disbelieve, for he had the prophecies pointing to the Messiah yet chose the opinions of men and the sayings of the rabbis rather than the counsel of God. In his own wisdom he therefore knew neither God nor Jesus Christ whom God had sent.
His unbelief was at the same time honest and without pretense, for he sincerely thought he ought to do many things contrary to the name of Jesus of Nazareth. Jesus stopped him in his persecuting career and showed him on whose side he was working. Confronted in this way, he accepted Christ's words and was converted from infidelity to faith.
He never afterward treated that unbelief with indifference, recognizing that it had led him to follow in Satan's track. It had led him to cause the suffering and death of the most precious of earth, of whom the world was not worthy. He never pleaded that his error of judgment was excusable and never made any excuse for his cruel course in faithfully following the impressions of a false conscience.