659. Faith according to the name (πίστις from πείθω, πείθομαι, fido, I am persuaded) primarily and by origin designates a voluntary trust or confidence, given either to an authority (or to a truth) or to the testimony of another through our intellect¹], or to his goodness or promise through the will itself²].

From the derivation of this latter meaning, faith is also taken: a) for fidelity in a promise³]; b) for the promise itself and the vow⁴]; c) for the things promised⁵].

From the derivation of the former meaning, faith is also taken: a) for truth in bearing witness⁶]; b) for the things witnessed themselves, e.g. for the doctrine to be believed, as in Eph. IV, 5 : « One Lord, one faith », and in the Athanasian Creed : « This is the Catholic faith... »; c) for the trust placed either in one's own opinion, when full evidence is lacking, or in the dictate of one's own conscience, as in Rom. XIV, 23 : « Whatsoever is not of faith (i.e. from the persuasion of conscience) is sin »; in which sense too a person is said to be in good or bad faith.

660. Faith in the strict sense is said of a voluntary assent of the intellect (actual faith), or of a habit inclining to the giving of such an assent (habitual faith)

on account of the sole authority or testimony of another. If that authority be human, it is called human faith; if it be divine, it is called divine faith.

Divine faith can be given about things merely natural; in the present order, however, in which we are destined for a supernatural end, it is about supernatural and divine things (and about other things in relation to eternal life), and so it is more strictly divine not only by reason of the motive but also by reason of the matter, and is therefore called theological.

661. Theological faith is described by the Apostle, in Heb. XI, 1 : Now faith is the substance of things hoped for, the argument of things not seen. It is called

1° the substance of things hoped for, i.e. the first in us inchoation of beatitude, and the first foundation (which stands under other things and so grounds them), as S. Thomas explains; or, more conformably to the Greek text : a firm and certain subsistentia (ὑπόστασις) of beatitude in our mind, inasmuch as faith makes us so certain of the things hoped for as if they were already present and possessed by us;

2° the argument (ἔλεγχος), metonymically for its effect, namely, the conviction it causes;

3° of things not seen (οὐ βλεπομένων) : faith is the argument, i.e. the full conviction, the certain persuasion, of things which are seen neither by the senses nor by the mind, but are admitted on account of God's authority.

That this description is a true definition is shown by S. Thomas, II-II, q. 4, a. 1 (cf. De Verit., q. 14, a. 2), and so from his time in the schools it has been customary to explain it as the classical definition. For by this definition faith is distinguished from all others:

a) by what is said the substance of things hoped for, it is distinguished from faith taken in a common sense, e.g. from human faith, which is not ordered to hoped-for beatitude;

b) by what is said the argument, it is distinguished from opinion, suspicion, and doubt, in which the intellect is not fully convinced nor firmly adheres to any truth;

c) finally, by what is said of things not seen, it is distinguished from science and from the intellect of principles, by which things appear to the intellect. Hence if one wished to put the Apostle's doctrine into the form of a definition, one could say : « faith is a habit of mind by which eternal life is begun in us, making the intellect assent to things unseen ».

662. The Vatican Council explains the Apostle's definition, while setting forth the nature of faith (Const. Dei Filius, c. 3) : « This faith, which is the beginning of human salvation, the Catholic Church professes to be a supernatural virtue, whereby, by the inspiring and aiding grace of God, we believe the things revealed by Him to be true, not for the intrinsic truth of those things perceived by the natural light of reason, but for the authority of God Himself revealing, who can neither deceive nor be deceived. For faith, as the witness of the Apostle, is the substance of things hoped for... ». The following are indicated:

1. the genus to which faith belongs : a supernatural virtue;

2. the proper act of the virtue of faith by which it is distinguished from other virtues : whereby we believe the things revealed to be true;

3. the matter about which it is concerned : things revealed by God;

4. the motive of faith : on account of the authority of God revealing;

5. the cause of faith : the inspiring, i.e. preventing, and aiding grace.

That this definition is real and adequate will be shown throughout the whole treatise⁷].

The treatise on faith does not, as some have thought, belong to dogmatic theology, but to moral theology. For to believe is a human act by which one must tend toward the supernatural end. And therefore, although the principal objects of faith are merely speculative or dogmas to be merely believed, which are treated in dogmatic theology, faith itself is something practical, which is to be known only insofar as it is at the same time to be done and brought into practice. Hence the entire treatise, as such, belongs to moral theology.

663. Division of the treatise. — The treatise on faith comprises five parts:

The 1st Part treats of the object of faith, which is better known than the act of faith, and so must first be explained : 1) of the formal object; 2) of the material object : a) of the material object in itself; b) of its conditions; c) of its evolution; d) of the Church proposing it.

The 2nd Part treats of the act of faith, which is better known than the habit of faith : A. of the interior act : 1) of its essence; 2) of its analysis, namely both a) of the act of faith itself, and b) of the pious affection of credulity, and c) of the judgment of credibility, i.e. of the preambles of faith; 3) of the necessity of the act of faith; B. of the exterior act or confession of faith.

The 3rd Part treats of the habit of faith : 1) of faith itself : a) in relation to the subject, b) in relation to the other supernatural virtues, c) in relation to the other intellectual habits; 2) of those who have faith; 3) of the cause and effects of faith; 4) of the gifts corresponding to faith.

The 4th Part treats of the vices and sins opposed : 1) of sins directly opposed to interior faith : a) of infidelity; b) of heresy and apostasy; 2) of sins indirectly opposed to faith : a) of communication with infidels and heretics; b) of co-operation toward infidelity and heresy; c) of the reading or publication of prohibited books; d) of the admission or profession of doctrine which is dangerous for faith; 3) of blasphemy, which is directly opposed to the confession of faith.

The 5th Part treats of the precept of faith.

Summa Theologiae Moralis I. — 33 PART ONE.

ON THE OBJECT OF FAITH.

S. Th. II-II, q. 1, a. 1.

664. The object of faith is the first truth, God, as will be proved below. He Himself is the first truth in a threefold way : a) in being, because His essence is the first being, and therefore the first eternal truth; b) in knowing, because by His wisdom from eternity He knows all things as they are; c) in saying, because by His veracity from eternity He has the highest propensity to say what is true, if He speaks.

665. The object of faith is twofold: material and formal. — For in every power and habit, as in every act, we distinguish the object:

1. The material object, or that which is actually attained, the matter about which the act is actually concerned, e.g. for cognition, that which is known, such as a conclusion. Further, the material object is twofold : for there is something which is attained first, through itself, and by reason of itself, which is therefore called the primary material object, and for the sake of which other things are attained, which are called the secondary material object.

2. There is the formal object, or that through which, by means of which, the material object is immediately attained, or the proximate motive on account of which it is attained, e.g. for cognition the medium through which something is immediately known, such as the syllogism by which the conclusion is known.

Let there be an example in vision : the secondary material object is the things seen, the primary is the colored, the formal is the light.

666. Observations. — 1st Lest confusion arise, it should be noted that some theologians call the primary material object the formal-quod object; but these call the formal object the formal-quo, or the formal motive, i.e. the formal reason⁸].

2nd In catechisms, the material object is designated by the particle what, e.g. when one is asked what we ought to believe, and the formal object is expressed by the particle why or wherefore, e.g. why we ought to believe.