"To err is human, to forgive divine." This saying of Alexander Pope expresses the heart of the Gospel. We must forgive, but only God has the power to forgive. Therefore, we are desperately in need of God's grace to forgive.
The Lord often gives us the grace to forgive others by reminding us of how much He has forgiven us. The Lord continues to say to each of us: "I canceled your entire debt when you pleaded with Me. Should you not have dealt mercifully with your fellow servant, as I dealt with you?" (Mt 18:32-33) Pope St. John Paul II taught: "God's forgiveness becomes in our hearts an inexhaustible source of forgiveness" (Message for the World Day of Peace, Jan. 1, 1997).
Look at a crucifix. See the love, pain, blood, and death of Jesus. Look at what Jesus did in our place. "He was pierced for our offenses, crushed for our sins, upon Him was the chastisement that makes us whole, by His stripes we were healed. We had all gone astray like sheep, each following his own way; but the Lord laid upon Him the guilt of us all" (Is 53:5-6).
We love and express love by forgiving others because Jesus first loved us (see 1 Jn 4:19). Accept the grace to forgive by recalling how much you have been loved and forgiven.