Summa summae S. Thomae, Tomus III

Blasphemy is a Greek word signifying the same as in Latin malediction. It is taken by theologians for a malediction detracting from the excellency of goodness, especially divine goodness. Hence I say 1°: Blasphemy can be defined¹: « A speaking of the heart or of the mouth by which, in the manner of an insult, something is said derogating from the excellency of the divine goodness. » Or more briefly: « A contumelious utterance against God. »

It is explained. It is said 1° « of the heart or of the mouth; » because we speak with both, and the demons, who speak only in mind, blaspheme.

It is said 2° « in the manner of an insult. » By this it is distinguished from simple infidelity, which consists in assent against the faith. For blasphemy does not require assent against the faith, but it suffices that something be said of God in the manner of an insult.

Nor is there required for this, mark well, an explicit and express intention of insulting and dishonoring God, but virtual and implicit suffices, insofar as by words, or by the manner of pronouncing them, according to the common apprehension, God is dishonored and contemned. Hence I do not assent to those who say that it is not blasphemy but only a vain use of the divine name, when someone, out of indignation against man, not against God, utters his head, his death, his blood, and the like. For those words so pronounced are contumelious to God, though uttered on occasion of another. Consequently there is there a virtual and implicit intention of dishonoring God. And otherwise blasphemies would be exceedingly rare, whereas they are reckoned most frequent. Hence St. Thomas, this a. 2, ad 3, says that he who suddenly breaks out into blasphemous words from some passion, adverting to their signification, commits mortal blasphemy; but he who utters these and the like words not only contumeliously, but either recitatively, or historically, is not a blasphemer: whence special attention must be given to the manner of pronouncing.

It is said « derogating from the excellency of the divine goodness. » And this is done not only when something contumelious is said directly against God, but also against the saints and sacred things; not indeed per se (for thus it would not be properly blasphemy, but the vice of irreligion, opposed to dulia), but with some relation at least virtual to God. For just as, says the Author, God is praised in his saints, insofar as the works which God works in the saints are praised, so also blasphemy committed against the saints redounds consequently to God. Therefore he who would say that St. Peter was impious and damned, that the Blessed Virgin was a harlot, would be a blasphemer. But he who spoke of them, not as saints, but as they were men on earth, e. g., if he called St. Peter bald, St. Crispin a shoemaker, would not be properly a blasphemer, since here there is no respect to God. But if he uttered these things out of hatred and indignation, he would sin mortally against dulia and the observance due to the saints; if however out of jest or levity, it would be venial sin.

Therefore blasphemy is committed: 1° by denying to God what befits him, or asserting of him what does not befit him: and this whether it be done enuntiatively, optatively, imperatively, or in imperfect speech; 2° by attributing to him what befits him, but mockingly and as something blameworthy, as by naming contemptuously the members of Christ and of the saints; 3° by attributing to a creature what is proper to God, as omnipotence; 4° by deeds equivalent to contumelious words, as spitting upon a crucifix.

I say 2°: Blasphemy is divided into heretical and non-heretical². Heretical is that which asserts something contrary to the faith, or denies something pertaining to the faith. Non-heretical is that by which, although nothing openly contrary to the faith is contained, nevertheless the things that are of faith are uttered contemptuously and contumeliously, as if they were blameworthy.

I say 3°: Blasphemy is of its genus the gravest mortal sin³, nor can it become venial from smallness of matter, but only from involuntary indeliberateness of the act.

The first part is clear, 1° from the gravest punishments by which it is punished⁴. In the old law, Lev., XXIV, 16, the blasphemer was stoned. In canon law several punishments are established against blasphemers; and if they despise these, they are to be deprived of ecclesiastical burial, cap. Statutum, tit. de maledicis, lib. V Decretal., and elsewhere. 2° Because it gravely repugns charity, since it is against the excellency of the divine goodness; likewise it is opposed to faith and religion, as I shall say presently.

The second part is also clear; because, however slight anything may be per se, that God should be dishonored and held in contempt is always the gravest evil.

The third part is clear in like manner; because in every species of sin involuntary indeliberateness excuses from the whole or grave sin, because from it it comes about that the act is not perfectly human.

I said « involuntary indeliberateness; » because, if it arise from a habit which the blasphemer does not care to eradicate as far as he can, it does not excuse from mortal sin, because it is voluntary in its cause, namely in that voluntary habit. Let confessors attend to this.

You will ask against what virtue blasphemy is opposed.

I answer. Insofar as it contains implicitly or explicitly something false concerning God, it is opposed to the confession of faith; insofar as it is a dishonoring of God, it is opposed to religion, whose formal object is worship, honor rendered to God.