PREAMBLES OF THE FAITH (praeambula fidei)
This expression denotes the truths which must and can be known by reason before, through infused faith and actual grace, the faithful adhere to the revealed truths “proper” to the whole world, i.e., truths revealed by the authority of God who has revealed them.
These preambles of the faith are the existence of God and the signs of the divine origin of Revelation. The existence of God, author of nature, can be easily known, even if confusedly, from the consideration of the nature of created things, their order, etc., which postulate the existence of a creator, supreme orderer (Wis 13:2-5). Hence the Vatican Council has defined (Denz-U, 1785): “that God, principle and end of all things, can be known with certainty by the natural light of human reason through created things.” The anti-Modernist oath adds (ibid., 2145): “The existence of God can be rationally demonstrated from the effects of which He is the cause.”
Among the preambles of the faith must also be reckoned the motives of credibility, i.e., the signs of the divine origin of the Revelation contained in the Old and New Testaments and in the living Tradition of the Church. These are miracles (in particular those of Christ, above all His Resurrection), fulfilled prophecies, the exceptional holiness of Jesus, the sublimity of His doctrine, the wonderful life of the one, holy, catholic, and apostolic Church, which for twenty centuries has resisted so many causes of division and ruin (Denz-U, 1790, 1794, 1799, 1812, 1813, 2145; V. CREDIBILITÀ RAZIONALE DELLA FEDE CATTOLICA; MIRACOLO; RIVELAZIONE).