What was the reason Christ changed Paul?

Paul had a zeal for tradition and law but Jesus saw his potential as a zealous minister. Saul, who became Paul, confesses: “You, of course, heard about my conduct formerly in Judaism, that to the point of excess I kept on persecuting the congregation of God and devastating it, and I was making greater progress in Judaism than many of my own age in my race, as I was far more zealous for the traditions of my fathers.” (Gal. 1:13, 14;
Saul had been utterly wrong, for Jesus identified himself with the very ones whom Saul was persecuting! In the face of the evidence, how could Saul keep “kicking against the goads”? Even a stubborn bull is eventually prodded in the direction its owner wants. By refusing to cooperate with Jesus’ urgings, therefore, Saul would be hurting himself.