Chapter 11 — Part I — Article IX (Of the Church)
Section 272. Q. If the Catholic Church contains all true believers in the world, must we not acknowledge it to be necessary for salvation that every believer should belong to her? A. Exactly so. Since Jesus Christ, in the words of St. Paul, is the Head of the Church, and he is the Saviour of the Body, it follows that, to have part in his salvation, we must necessarily be members of his body, that is, of the Catholic Church. Eph. v. 23. The Apostle Peter writes that baptism saveth us after the figure of the ark of Noah. All who were saved from the general deluge were saved only in the ark; so all who obtain everlasting salvation obtain it only in the one Catholic Church.