Catechism of the Catholic Church §2844 — excerpt
Christian prayer extends to the forgiveness of enemies, transfiguring the disciple by configuring him to his Master. Forgiveness is a high-point of Christian prayer; only hearts attuned to God's compassion can receive the gift of prayer.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: John Paul II, DM 14
