In today's Gospel we get the scene where Jesus asks Peter, not once, not twice, but three times, do you love me?
At that moment even Peter himself may not have truly understood what was going on. It wasn't that Jesus doubted the sincerity of his first answer. Even before Jesus asked the question, he knew the answer. He knew Peter's heart. But two things are going on: one, Peter needed to hear himself say it, "Yes, Lord, you know that I love you."
Second, and more importantly he needed to make the triple affirmation, to unwind the triple denial. Some say, "You cannot change the past. What's done is done." They forget one thing, God exists outside of time. Our linear unidirectional concept of time means nothing to God. Time and space are our limitations not his.
God not only forgives the wounds of our sins, but heals them.
If Jesus could heal the triple denial of Peter, what sin of ours can he not heal?