Catechism of the Catholic Church §442 — excerpt
Such is not the case for Simon Peter when he confesses Jesus as "the Christ, the Son of the living God", for Jesus responds solemnly: "Flesh and blood has not revealed this to you, but my Father who is in heaven."
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.