What does Psalm 103:10 mean?

This verse contains a strong admission of Israel's sin and guilt as well as a tribute to God's forgiveness. If God punished every sinner as that sinner deserves to be punished, no sinner would be allowed to enter heaven. Even worse, the Bible says, "For all have sinned and fall short of the glory of God" (Romans 3:23). Humanity getting what we deserve would mean every single one of us being separated from God, forever.

The Old Testament prophet Ezra understood that God does not punish us to the extent we deserve. He said, "And after all that has come upon us for our evil deeds and for our great guilt, seeing that you, our God, have punished us less than our iniquities deserved" (Ezra 9:13). Contrary to punishing us as we deserve, God loved us and gave His Son for us (John 3:16–17).

Jesus took the full punishment for our sins by dying in our place on the cross. Romans 5:6 announces: "For while we were still weak, at the right time Christ died for the ungodly. Romans 5:8 says "God shows his love for us in that while we were still sinners, Christ died for us." Those who accept this are saved (John 3:16–18), but those who reject it are not (John 3:36).