It wasn't Saul becoming Paul but end times
Despite popular belief, Saul did not become Paul on the road to Damascus. Those are simply two versions of the same name: Saul the Hebrew version, Paul the Roman. However, what did change when Christ appeared to Paul—and it’s perhaps the most overlooked part of the story— was Paul’s eschatology. In Paul’s encounter with Christ, he saw the end breaking into the present. Paul, his vision was nothing less than “a day of the Lord.” What is “a day of the Lord”? “Day of the Lord” terminology is grounded in the Old Testament. A day of the Lord is an event when he comes in righteous and merciful judgment. While the prophets referred to many “days of the Lord,” in their near future, these all foreshadowed one climactic and final “Day.” Historic and localized events in Israel’s history such as famine, war, and exile all predicted the ultimate Day. In this climactic Day of the Lord, he will visit the world to vindicate his people, judge the nations, and establish his kingdom of peace (e.g.