Summa Theologiae Moralis, vol. I: De Principiis

S. Th. II-II, q. 11 and 12.

743. Various conditions of infidelity. — On the part of the sinner, infidelity is called either apostasy, or heresy, or simple infidelity. An apostate is one who formerly totally rejects the faith of Christ received ; a heretic, one who at some time (at least now) professes the faith of Christ received, but corrupts the dogmata which it pertains to the Church to propose ; simply an infidel, one who never received the faith of Christ. But so that one may be held an apostate or heretic fully, that is, even in the external forum and before the Church, it is required that he has received the faith (at least externally) by a solemn profession in Baptism, and has denied this faith, which has been explicitly proposed by the Church to be believed, either totally or partially (can. 1325, § 2).

744. Heresy (ketterij) etymologically signifies choice, whence in the whole Catholic tradition it designates the error of one who, having received the faith especially in Baptism, adheres to Christ and is unwilling to receive the rule of faith from the Church, but chooses for himself, i.e. from perfect deliberation firmly establishes the rule of belief¹(/works/summa-theologiae-prima-pars) says that choice signifies what one wills firmly after perfect consideration..

It is usually defined : a voluntary and pertinacious error in the Catholic faith, in one who professes the faith of Christ. The following are indicated :

1) the material element :

a) error, i.e. an erroneous judgment of the intellect, not mere ignorance, whence a heretic is not one who only externally denies the faith from some external pressure

b) in faith, i.e. in revealed truth, whence he is not a heretic who only denies a truth connected with the revealed, even if infallibly defined by the Church, such as a theological conclusion or a dogmatic fact. Thus heresy is distinguished from simple error, against ecclesiastical faith or the obedience due to the Church teaching ;

c) Catholic, i.e. in some revealed truth directed to all which the Church proposes to be believed ; so that in the one denying there is at the same time contempt of the authority of God and of the Church : thus heresy is distinguished from infidelity, which can also be opposed to divine faith alone ;

d) voluntary, otherwise it would not be an act of infidelity by which one is unwilling to believe God and the Church and departs from them ; whence he who, adhering to the Church, from ignorance even culpable would not know that something has been proposed by the Church to be believed, and would deny it, would not be a heretic even materially : thus heresy is distinguished from mere ignorance of faith ;

2) the formal element : pertinacious, so that one opposes the authority of God and the Church, not indeed from ignorance even culpable, but knowingly and willingly, i.e. by an evil will, when the truth and this authority is sufficiently proposed to him, whether from pride or vainglory, or from a desire to contradict, or from levity, or from whatever other cause ; whence he who, from ignorance even culpable, would not know that obedience is to be given to the Church in faith, could sin, but would not be a formal heretic but only material : thus heresy properly so called and formal is distinguished from heresy merely material ;

3) the subject : in one who professes the faith of Christ, i.e.

in one who has received it, especially by Baptism, and has not totally rejected it : thus heresy is distinguished from apostasy and from simple infidelity.

745. Heresy differs from infidelity, as species from genus : for heresy adds something to infidelity.

1) Infidelity can be in every man, using reason ; heresy is only in a Christian, especially baptized.

2) Infidelity says only the negation of faith in those things which God has revealed ; heresy, however, the negation of faith in those things which are proposed by the Church as revealed and to be believed ; whence one who denies a private revelation made to him would not commit heresy but the sin of infidelity, and he who denies a truth which he certainly knows pertains to public revelation but which the Church does not explicitly propose to be believed, would be a heretic but not in the full sense and before the Church.

3) Infidelity is opposed to divine faith, heresy to Catholic faith.

746. Heresy is variously divided. — Heresy is either material²] or formal. Material heresy denies the authority of the Church in proposing faith without pertinacity, because it has not been sufficiently proposed ; formal heresy sufficiently knows the authority of the Church, but refuses to embrace the faith of the true Church and denies it in at least one point. — It is either internal, which lies hidden in the mind so that it is manifested by no external sign ; or external, which is manifested by external signs (by words, signs, deeds, omission of a deed), even if no one sees them ; this is either hidden, which is manifested to no one or to only one or another, or public, which is manifested openly and before many externally.

The signs because of which one is to be considered a material heretic, are usually indicated as : 1) if he is ready to submit himself to the judgment of the Church, when he recognizes his error, even if meanwhile he holds his opinion stubbornly ; 2) if he has known nothing of the Catholic faith, and has never doubted of his own ; 3) if, doubting, he has tried to recognize the truth, as much as he could. — But he who, from human fear or negligence, postpones his conversion to the faith, is not therefore a heretic ; he sins, however, against the affirmative precept of faith, if he defers it for a long time.

On the contrary, one is to be considered pertinacious and therefore a formal heretic : 1) who doubts, and from pertinacity, or from contempt of the Church, refuses to inquire further ; — 2) who, of set purpose, turns his intellect away from a sufficiently proposed truth, so that he may adhere to his sect or opinion ; — 3) who, having recognized the truth, persists in contradicting the Church, as the heresiarchs are wont to do out of hatred of the Pope or of the Church. — These are the three principal degrees of pertinacity, of which the first is founded in a truth studiously neglected ; the second, in a truth sufficiently proposed but despised ; the third, in a recognized truth maliciously opposed.

747. The sin of heresy is most grave, (n. 737 and 739), since it of itself merits corporal together with spiritual punishments.

Concerning corporal punishments S. Thomas teaches : « It is much graver to corrupt faith, by which is the life of the soul, than to falsify money, by which temporal life is aided. Hence if forgers of money or other evildoers are justly handed over to death by secular rulers, much more so heretics, as soon as they are convicted of heresy, can not only be excommunicated but also justly killed » (a. 3). Death, however, although it can be decreed by the Church, is not to be inflicted by her.

Spiritual punishments are inflicted by Canon Law ; according to which heretics :

1) incur by the fact itself excommunication specially reserved to the Roman Pontiff (can. 2314, § 1),

2) unless, when warned, they repent, they are to be deprived of any benefice, dignity, pension, office, or other function which they have in the Church, they are to be declared infamous, and clerics, after a repeated warning, are to be deposed (ib.),

3) indeed, if they have given their name to a non-Catholic sect or publicly adhered to it, they are by the fact itself infamous, and clerics, after a previous warning, are to be degraded (ib.),

4) they are irregular (can. 985),

5) they are deprived of ecclesiastical burial (can. 1240, § 1).

For incurring which punishments, formal heresy together with external is required, but for the 3rd and 5th also public³ arises against it, is bound under grave obligation to inquire about the faith and to ask light of God ; if he neglects this, he sins by the sin of ignorance in faith, which is grave if the negligence is grave. But he cannot practically admit the doubt and abandon the faith, even if, having made the inquiry, the opposite of faith appears probable, but he is bound to inquire until he arrives at a certitude proportioned to his mind. The reason is, that in matters of salvation the safer course must be taken. Similarly, the law of nature requires that we always have religion toward God. Hence we must retain what has been admitted on authority until we can by our own reason sufficiently effect conviction, which mere probability is not.

The same is to be said of a heretic and an infidel who doubt about their religion.