Catechism of the Catholic Church §2090 — excerpt
When God reveals Himself and calls him, man cannot fully respond to the divine love by his own powers. He must hope that God will give him the capacity to love Him in return and to act in conformity with the commandments of charity.
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.