Catechism of the Catholic Church §1990 — excerpt
Justification detaches man from sin which contradicts the love of God, and purifies his heart of sin. Justification follows upon God's merciful initiative of offering forgiveness.
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.