Why did God save Saul of Tarsus?

God saved Saul of Tarsus by grace alone, because Saul had no merit whatsoever. Although Saul was a religious Jew, a fanatic, and a zealot, God's grace stopped him in his tracks and saved him. Scripture thus presents Saul's conversion as an act of undeserved grace, not human worthiness.

Les explains that Saul of Tarsus was a religious Jew, a fanatic, and a zealot, yet the grace of God stopped him in his tracks on the road to Damascus. Saul was saved because he had no merit whatsoever, and that is grace. At that point Saul did not yet know that Christ died for his sins and had risen; he had only recognized who Jesus really was. God also dealt with Ananias in Acts chapter 9, telling him to go to Saul, who was praying and had seen a vision of Ananias coming to restore his sight. Ananias objected, having heard how much evil Saul had done to the saints at Jerusalem.

Why was Saul of Tarsus saved on the road to Damascus?

Saul of Tarsus was saved on the road to Damascus by the grace of God, not by any merit of his own. The account shows God stopped him in his tracks and saved him despite his religious zeal, before he understood the full gospel of Christ's death and resurrection; he had only recognized who Jesus really was.