Why did God save Paul the persecutor?

Despite his persecution and hatred of Jesus of Nazareth, God saved Paul not because he deserved or earned it, but by His grace. Paul was set apart from his mother’s womb in God’s preordained plan and called by grace to reveal His Son in him.

Les explains that Saul of Tarsus was already on God’s mind in eternity past. At the appropriate time, Saul’s mother conceived, and the baby in her womb was all part of God’s preordained plan. God formed him in the womb and brought him to birth. Though Paul had hated Jesus of Nazareth with a passion as a persecutor, God saw fit to save him, not because he deserved it or earned it, but by grace. God’s purpose was to reveal His Son in Paul—the crucified, resurrected, and risen Christ.

Galatians 1:15

But when it pleased God, who separated me from my mother’s womb, and called me by his grace,

Why did God save Paul even though he persecuted the church?

God saved Paul by grace alone, not because he deserved or earned it, despite his persecution of the church. Saul of Tarsus was already on God's mind in eternity past, separated from his mother's womb and called by grace according to God's preordained plan to reveal His Son in him.