Catechism of the Catholic Church §680 — excerpt
Christ the Lord already reigns through the Church, but all the things of this world are not yet subjected to him. the triumph of Christ's kingdom will not come about without one last assault by the powers of evil.
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.