Grace

When God forgives, it is complete. He bears no grudges, He wipes the slate clean, and sees us as holy and righteous once again .. until our next sin. Then, He griefs. It pains His heart that we succumbed once more to temptation, that we strayed once again from the path He set for us. If we repent, He is faithful and just to forgive us again, just as He had, a million times before.

That's the love and mercy of God.

When Man forgives, it is incomplete. That's the problem.