Catechism of the Catholic Church §286 — excerpt
Human intelligence is surely already capable of finding a response to the question of origins. the existence of God the Creator can be known with certainty through his works, by the light of human reason, even if this knowledge is often obscured and disfigured by error.
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: Vatican Council I, can. 2 # I: DS 3026