David said, "I will confess my transgressions to the Lord" (Psalm 32:5). Why? Because "When I kept silent, my bones wasted away through my groaning all day long. For day and night your hand was heavy upon me; my strength was dried up as by the heat of summer" (Psalm 32:3-4). People living with unconfessed sin groan. They groan about this, they groan about that. But really, they are admitting that they have sins still unconfessed. Their strength is dried up. They are sluggish, unmotivated, always looking for ways to minimize their obedience, because the joy is gone.
Living with unconfessed sin saps a believer's spiritual strength. But living moment by moment in confession and honesty and realism – "Oh, what joy for those whose disobedience is forgiven, whose sin is put out of sight! Yes, what joy for those whose record the Lord has cleared of guilt, whose lives are lived in complete honesty!" (Psalm 32:1-2, NLT).