c) In analyzing the notions of _fides_ and _necessitas_ theologians distinguish between _fides explicita_ and _fides implicita_, and between _necessitas medii_ and _necessitas praecepti_.
_Fides explicita_ is an express and fully developed belief in the truths of revelation; _fides implicita_, a virtual belief in whatever may be contained in a dogma explicitly professed. I make an act of implicit faith when I say, for instance: “I believe whatever the Church teaches,” or: “I heartily accept whatever God has revealed.”
The _necessitas medii_ is based on the objective relation of means to an end, and consequently binds all men, even the ignorant and those who are in error without their own fault. Such, for example, is the necessity of the eye for seeing, of wings for flying, of grace for performing salutary acts, of the _lumen gloriae_ for the beatific vision. The _necessitas praecepti_, on the other hand, is founded entirely on the will of God, who positively commands or forbids under pain of grievous sin, but is willing to condone non-compliance with his precepts when it is owing to guiltless ignorance. This applies to all positive divine precepts, _e.g._ the law of fasting and abstinence. It is to be noted that the _necessitas medii_ always involves the _necessitas praecepti_, because God must needs will and impose upon us by positive precept whatever is objectively necessary as a means of salvation.
α) The first question that arises with regard to this twofold faith and necessity is: Are sinners preparing for justification, and the faithful in general, obliged by necessity of precept to believe explicitly all revealed truths? The answer is, No; because this is practically impossible, and God does not demand the impossible.
Generally speaking, it is sufficient to have an explicit knowledge of, and give one’s firm assent to, the more important dogmas and moral precepts—the twelve articles of the Apostles’ Creed, the Commandments of God and the Church, the Sacraments (as needed), and the Our Father. All other revealed truths need be held only _fide implicitâ_.(795) More is of course demanded of educated persons and those who are in duty bound to instruct others, such as priests and teachers.(796)