After explaining how Saul persecuted the church, here’s how J. Gresham Machen briefly summarized the story of Saul/Paul’s conversion in Acts 9:
And yet he [Paul] attained salvation. It came in the strangest way. He was at the height of his persecuting zeal. He was making havoc of the Church of God (Gal. 1.13). He had consented to the death of the first Christian martyr (Acts 7.58; 8.1; 22.20; 26.10). He was breathing threatening and slaughter (Acts 9:1). Not satisfied with the destruction that he had wrought in Jerusalem, he obtained authority from the Sanhedrin to extend the persecution to Damascus.
And then, suddenly, when it was least expected, the wonderful thing happened. Paul was nearing Damascus with his companions. It was midday. Suddenly a light more intense than the light of the sun shone around him. His companions saw the light. But Paul saw more than they. He saw the Lord Jesus Christ (I Cor. 9.1; 15.8; Acts 9.17, 27; 22.14; 26.16). He became a witness to the resurrection. His companions heard a voice; but Paul alone understood what was said (Acts 9.7; 22.9). It was the voice of the Lord calling him to be a servant and an apostle. It was useless to resist. Jesus had broken every barrier down. ‘It is hard for thee to kick against the goad’ (Acts 26.14). The crucified Teacher whom
Paul had despised was really risen from the dead, the Lord of glory, the true Messiah of Israel. The shameful death on the cross was really the divine sacrifice for the sins of men. All of Paul’s life crumbled away beneath him. In miserable blindness he groped his way into Damascus, a poor, wretched, broken-spirited man! All his zeal had been nothing but rebellion against the King of Israel. Yet Jesus had appeared to him, not to put him to shame, but to save him. The poor, bewildered, broken-spirited rabbi became the most influential man in the history of the world!
From Oveido, FL