First, Christ took upon his own head the sins of those who have wronged us. Second, because of this, he stands between us and those whom we think have wronged us, asking us to realize that the atonement is sufficient for those sins and to therefore repent of our grudges and give up our enmity. And finally, if we forgive, the atonement fills us with what we have lacked and either washes away our pain, or sustains us in it.