What does Psalm 66:20 mean?

This psalm concludes with this repeated celebration that God answered the writer's prayer (Psalm 66:19). Though this psalm is not officially tied to David, it includes themes of his other writings. David experienced intense guilt and suffering for his sin regarding Bathsheba (2 Samuel 12:7–11). When the Lord answered David's prayer and forgave him (Psalm 51:1), he felt the sense of God's forgiveness. David writes in Psalm 32:11, "Be glad in the LORD and rejoice, O righteous, and shout for joy, all you upright in heart." This psalmist, too, had reasons to be thankful for God's mercy and forgiveness.

When a believer sins, God does not cast him aside. Instead, He convicts him of sin and disciplines him with the goal of restoring him to fellowship with Himself (Hebrews 12:6). Luke 15 records a story referred to as that of "the prodigal son;" the story may just as well be titled "the loving father." When the wayward son regretted his wasted life, he decided to return home. Perhaps to his surprise, "while he was a long way off, his father saw him and felt compassion, and ran and embraced him and kissed him" (Luke 15:20). The heavenly Father, like the prodigal's father, loves every repentant believer, and eagerly forgives them.