786. For all adults the act of faith is necessary for salvation as a necessity of means (see 360), for the Apostle says: “Without faith it is impossible to please God” (Heb., xi. 6). The truths which must be believed under necessity of means are of two kinds. (a) One must believe with implicit faith all revealed truths which one does not know and is not bound to know. An act of implicit faith is contained in the formula: “O my God, I firmly believe all the truths the Catholic Church teaches, because Thou hast revealed them.” (b) One must believe with explicit faith all the truths which one is bound to know. An act of explicit faith in all the truths necessary by necessity of means is contained in the Apostles’ Creed. Other truths that must be explicitly believed on account of a necessity of precept will be discussed in 918, 920. 787. What specifically are the truths just referred to that all are bound to know as a necessary means? (a) Theologians generally agree that it has always been necessary for adults to know and accept two basic mysteries--God’s existence, as the supernatural End or happiness of man, and His providence as exercised in supplying the means necessary for supernatural salvation (see 768). Without such belief, supernatural hope and charity, at all times necessary, are impossible. (b) A majority of theologians hold, and with greater probability it seems, that since the promulgation of the Gospel it is necessary for adults to know and accept the two basic mysteries of Chrisitanity-- viz., that in God, who is our beatitude, there are three persons (the Trinity), and that the way to our beatitude is through Christ our Redeemer (the Incarnation). 788. Even before the Gospel, it was always necessary as a means that one believe explicitly in God as our supernatural happiness and as the provider of the means thereto. Thus, the Apostle, speaking of the ancient patriarchs, says: “He that cometh to God, must believe that He is, and is a rewarder to them that seek Him” (Heb., xi. 6). He that would come to God (i.e., be saved), must believe in God as the Author of glory and of grace. Hence, one must believe: (a) that God exists, who is not ashamed to be called our God, and who prepares for us a better, that is, a heavenly country (Heb., xi. 6); (b) that God is a remunerator, from whom must be expected the working out of His promises and the helps to attain the reward, as well as the meting out of justice. In this faith is included implicitly a faith in Christ, and thus in the Old Testament a belief, at least implicit, in the Messiah to come was always necessary: “Man is not justified by the works of the law, but by the faith of Jesus Christ” (Gal., ii. 16).