Jesus forgave his apostles, thus making peace between them and God. Then he gave them a mission: to reconcile others with God by preaching the Gospel and celebrating the sacraments, especially the Sacrament of Reconciliation (the forgiveness of sins). In this sacrament, the successors of the apostles (bishops and priests) offer us peace with God the Father through the ministry of the Holy Spirit. This is reflected in the words of absolution the priest speaks in Confession:
God, the Father of mercies, through the Death and Resurrection of his Son, has reconciled the world to himself and poured out the Holy Spirit for the forgiveness of sins; through the ministry of the Church may God grant you pardon and peace, and I absolve you from your sins in the name of the Father, and of the Son, and of the Holy Spirit.
Thanks be to God for making peace with us when we didn't deserve it!