Catechism of the Catholic Church §651 — excerpt
"If Christ has not been raised, then our preaching is in vain and your faith is in vain." The Resurrection above all constitutes the confirmation of all Christ's works and teachings.
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.