How do we know God's grace can save the worst sinners?

The conversion of Saul encourages believers regarding the extent of God's grace. If God can save Saul, who was actively persecuting Christians and believed he was righteous, then His grace can reach any sinner, regardless of their past. The narrative shows that God focused on Saul's heart, illuminating his understanding of sin and leading him to repentance and faith. This exemplifies the Reformed belief in the complete inability of man to save himself and the powerful nature of God's sovereign initiative in salvation. Ultimately, God's choice to save sinners like Saul illustrates that salvation relies solely on His grace, not on human effort or merit.