From The Great House of God by Max Lucado

Confession does not create a relationship with God, it simply nourishes it. If you are a believer, admission of sins does not alter your position before God, but it does enhance your peace with God. When you confess, you agree; you quit arguing with God and agree with Him about your sin. Unconfessed sin leads to a state of disagreement. You may be God’s child, but you don’t want to talk to Him. He still loves you, but until you admit what you’ve done, there’s going to be tension in the house.

But just as unconfessed sin hinders joy, confessed sin releases it. When we admit sin we are like a first grader standing before the teacher with a messy paper. “I colored outside the lines too many times. Could I start over on a clean sheet?” “Of course,” says the teacher. Happy is the first grader who gets a second chance, or as David wrote, “Happy is the person whose sins are forgiven, whose wrongs are pardoned” (Psalm 32:1). So we dash back to our seat and start over.