Summa Th. II-II EN Qu.91 a.2

SUPERSTITION, i.e. BY WAY OF EXCESS (Questions [92]-96)


In due sequence we must consider the vices that are opposed to religion. First we shall consider those which agree with religion in giving worship to God; secondly, we shall treat of those vices which are manifestly contrary to religion, through showing contempt of those things that pertain to the worship of God. The former come under the head of superstition, the latter under that of irreligion. Accordingly we must consider in the first place, superstition and its parts, and afterwards irreligion and its parts.

Under the first head there are two points of inquiry:

(1) Whether superstition is a vice opposed to religion?

(2) Whether it has several parts or species?

Whether superstition is a vice contrary to religion?

Objection: 1. It would seem that superstition is not a vice contrary to religion. One contrary is not included in the definition of the other. But religion is included in the definition of superstition: for the latter is defined as being "immoderate observance of religion," according to a gloss on Col 2,23, "Which things have indeed a show of wisdom in superstition." Therefore superstition is not a vice contrary to religion.
2. Further, Isidore says (Etym. x): "Cicero [*De Natura Deorum ii, 28] states that the superstitious were so called because they spent the day in praying and offering sacrifices that their children might survive [superstites] them." But this may be done even in accordance with true religious worship. Therefore superstition is not a vice opposed to religion.
3. Further, superstition seems to denote an excess. But religion admits of no excess, since, as stated above (Question [81], Article [5], ad 3), there is no possibility of rendering to God, by religion, the equal of what we owe Him. Therefore superstition is not a vice contrary to religion.

On the contrary Augustine says (De Decem Chord. Serm. ix): "Thou strikest the first chord in the worship of one God, and the beast of superstition hath fallen." Now the worship of one God belongs to religion. Therefore superstition is contrary to religion.
I answer that As stated above (Question [81], Article [5]), religion is a moral virtue. Now every moral virtue observes a mean, as stated above (FS, Question [64], Article [1]). Therefore a twofold vice is opposed to a moral virtue. One by way of excess, the other by way of deficiency. Again, the mean of virtue may be exceeded, not only with regard to the circumstance called "how much," but also with regard to other circumstances: so that, in certain virtues such as magnanimity and magnificence; vice exceeds the mean of virtue, not through tending to something greater than the virtue, but possibly to something less, and yet it goes beyond the mean of virtue, through doing something to whom it ought not, or when it ought not, and in like manner as regards other circumstances, as the Philosopher shows (Ethic. iv, 1,2,3).Accordingly superstition is a vice contrary to religion by excess, not that it offers more to the divine worship than true religion, but because it offers divine worship either to whom it ought not, or in a manner it ought not.

Reply to Objection: 1. Just as we speak metaphorically of good among evil things---thus we speak of a good thief---so too sometimes the names of the virtues are employed by transposition in an evil sense. Thus prudence is sometimes used instead of cunning, according to Lc 16,8, "The children of this world are more prudent [Douay: 'wiser'] in their generation than the children of light." It is in this way that superstition is described as religion.
2. The etymology of a word differs from its meaning. For its etymology depends on what it is taken from for the purpose of signification: whereas its meaning depends on the thing to which it is applied for the purpose of signifying it. Now these things differ sometimes: for "lapis" [a stone] takes its name from hurting the foot [laedere pedem], but this is not its meaning, else iron, since it hurts the foot, would be a stone. In like manner it does not follow that "superstition" means that from which the word is derived.
3. Religion does not admit of excess, in respect of absolute quantity, but it does admit of excess in respect of proportionate quantity, in so far, to wit, as something may be done in divine worship that ought not to be done.

Whether there are various species of superstition?

Objection: 1. It would seem that there are not various species of superstition. According to the Philosopher (Topic. i, 13), "if one contrary includes many kinds, so does the other." Now religion, to which superstition is contrary, does not include various species; but all its acts belong to the one species. Therefore neither has superstition various species.
2. Further, opposites relate to one same thing. But religion, to which superstition is opposed, relates to those things whereby we are directed to God, as stated above (Question [81], Article [1]). Therefore superstition, which is opposed to religion, is not specified according to divinations of human occurrences, or by the observances of certain human actions.
3. Further, a gloss on Col 2,23, "Which things have . . . a show of wisdom in superstition," adds: "that is to say in a hypocritical religion." Therefore hypocrisy should be reckoned a species of superstition.

On the contrary Augustine assigns the various species of superstition (De Doctr. Christ. ii, 20).
I answer that As stated above, sins against religion consist in going beyond the mean of virtue in respect of certain circumstances (Article [1]). For as we have stated (FS, Question [72], Article [9]), not every diversity of corrupt circumstances differentiates the species of a sin, but only that which is referred to diverse objects, for diverse ends: since it is in this respect that moral acts are diversified specifically, as stated above (FS, Question [1], Article [3]; FS, Question [18], Articles [2],6).Accordingly the species of superstition are differentiated, first on the part of the mode, secondly on the part of the object. For the divine worship may be given either to whom it ought to be given, namely, to the true God, but "in an undue mode," and this is the first species of superstition; or to whom it ought not to be given, namely, to any creature whatsoever, and this is another genus of superstition, divided into many species in respect of the various ends of divine worship. For the end of divine worship is in the first place to give reverence to God, and in this respect the first species of this genus is "idolatry," which unduly gives divine honor to a creature. The second end of religion is that man may be taught by God Whom he worships; and to this must be referred "divinatory" superstition, which consults the demons through compacts made with them, whether tacit or explicit. Thirdly, the end of divine worship is a certain direction of human acts according to the precepts of God the object of that worship: and to this must be referred the superstition of certain "observances."Augustine alludes to these three (De Doctr. Christ. ii, 20), where he says that "anything invented by man for making and worshipping idols is superstitious," and this refers to the first species. Then he goes on to say, "or any agreement or covenant made with the demons for the purpose of consultation and of compact by tokens," which refers to the second species; and a little further on he adds: "To this kind belong all sorts of amulets and such like," and this refers to the third species.

Reply to Objection: 1. As Dionysius says (Div. Nom. iv), "good results from a cause that is one and entire, whereas evil arises from each single defect." Wherefore several vices are opposed to one virtue, as stated above (Article [1]; Question [10], Article [5]). The saying of the Philosopher is true of opposites wherein there is the same reason of multiplicity.
2. Divinations and certain observances come under the head of superstition, in so far as they depend on certain actions of the demons: and thus they pertain to compacts made with them.
3. Hypocritical religion is taken here for "religion as applied to human observances," as the gloss goes on to explain. Wherefore this hypocritical religion is nothing else than worship given to God in an undue mode: as, for instance, if a man were, in the time of grace, to wish to worship God according to the rite of the Old Law. It is of religion taken in this sense that the gloss speaks literally.


We must now consider the species of superstition. We shall treat (1) Of the superstition which consists in giving undue worship to the true God; (2) Of the superstition of idolatry; (3) of divinatory superstition; (4) of the superstition of observances.

Under the first head there are two points of inquiry:

(1) Whether there can be anything pernicious in the worship of the true God?

(2) Whether there can be anything superfluous therein?

Whether there can be anything pernicious in the worship of the true God?

Objection: 1. It would seem that there cannot be anything pernicious in the worship of the true God. It is written (Joel 2:32): "Everyone that shall call upon the name of the Lord shall be saved." Now whoever worships God calls upon His name. Therefore all worship of God is conducive to salvation, and consequently none is pernicious.
2. Further, it is the same God that is worshiped by the just in any age of the world. Now before the giving of the Law the just worshiped God in whatever manner they pleased, without committing mortal sin: wherefore Jacob bound himself by his own vow to a special kind of worship, as related in Genesis 28. Therefore now also no worship of God is pernicious.
3. Further, nothing pernicious is tolerated in the Church. Yet the Church tolerates various rites of divine worship: wherefore Gregory, replying to Augustine, bishop of the English (Regist. xi, ep. 64), who stated that there existed in the churches various customs in the celebration of Mass, wrote: "I wish you to choose carefully whatever you find likely to be most pleasing to God, whether in the Roman territory, or in the land of the Gauls, or in any part of the Church." Therefore no way of worshiping God is pernicious.

On the contrary Augustine [*Jerome (Ep. lxxv, ad Aug.) See Opp. August. Ep. lxxxii] in a letter to Jerome (and the words are quoted in a gloss on Ga 2,14) says that "after the Gospel truth had been preached the legal observances became deadly," and yet these observances belonged to the worship of God. Therefore there can be something deadly in the divine worship.
I answer that As Augustine states (Cont. Mendac. xiv), "a most pernicious lie is that which is uttered in matters pertaining to Christian religion." Now it is a lie if one signify outwardly that which is contrary to the truth. But just as a thing is signified by word, so it is by deed: and it is in this signification by deed that the outward worship of religion consists, as shown above (Question [81], Article [7]). Consequently, if anything false is signified by outward worship, this worship will be pernicious.Now this happens in two ways. In the first place, it happens on the part of the thing signified, through the worship signifying something discordant therefrom: and in this way, at the time of the New Law, the mysteries of Christ being already accomplished, it is pernicious to make use of the ceremonies of the Old Law whereby the mysteries of Christ were foreshadowed as things to come: just as it would be pernicious for anyone to declare that Christ has yet to suffer. In the second place, falsehood in outward worship occurs on the part of the worshiper, and especially in common worship which is offered by ministers impersonating the whole Church. For even as he would be guilty of falsehood who would, in the name of another person, proffer things that are not committed to him, so too does a man incur the guilt of falsehood who, on the part of the Church, gives worship to God contrary to the manner established by the Church or divine authority, and according to ecclesiastical custom. Hence Ambrose [*Comment. in 1Co 11,27, quoted in the gloss of Peter Lombard] says: "He is unworthy who celebrates the mystery otherwise than Christ delivered it." For this reason, too, a gloss on Col 2,23 says that superstition is "the use of human observances under the name of religion."

Reply to Objection: 1. Since God is truth, to invoke God is to worship Him in spirit and truth, according to Jn 4,23. Hence a worship that contains falsehood, is inconsistent with a salutary calling upon God.
2. Before the time of the Law the just were instructed by an inward instinct as to the way of worshiping God, and others followed them. But afterwards men were instructed by outward precepts about this matter, and it is wicked to disobey them.
3. The various customs of the Church in the divine worship are in no way contrary to the truth: wherefore we must observe them, and to disregard them is unlawful.

Whether there can be any excess in the worship of God?

Objection: 1. It would seem that there cannot be excess in the worship of God. It is written (Si 43,32): "Glorify the Lord as much as ever you can, for He will yet far exceed." Now the divine worship is directed to the glorification of God. Therefore there can be no excess in it.
2. Further, outward worship is a profession of inward worship, "whereby God is worshiped with faith, hope, and charity," as Augustine says (Enchiridion iii). Now there can be no excess in faith, hope, and charity. Neither, therefore, can there be in the worship of God.
3. Further, to worship God consists in offering to Him what we have received from Him. But we have received all our goods from God. Therefore if we do all that we possibly can for God's honor, there will be no excess in the divine worship.

On the contrary Augustine says (De Doctr. Christ. ii, 18) "that the good and true Christian rejects also superstitious fancies, from Holy Writ." But Holy Writ teaches us to worship God. Therefore there can be superstition by reason of excess even in the worship of God.
I answer that A thing is said to be in excess in two ways. First, with regard to absolute quantity, and in this way there cannot be excess in the worship of God, because whatever man does is less than he owes God. Secondly, a thing is in excess with regard to quantity of proportion, through not being proportionate to its end. Now the end of divine worship is that man may give glory to God, and submit to Him in mind and body. Consequently, whatever a man may do conducing to God's glory, and subjecting his mind to God, and his body, too, by a moderate curbing of the concupiscences, is not excessive in the divine worship, provided it be in accordance with the commandments of God and of the Church, and in keeping with the customs of those among whom he lives.On the other hand if that which is done be, in itself, not conducive to God's glory, nor raise man's mind to God, nor curb inordinate concupiscence, or again if it be not in accordance with the commandments of God and of the Church, or if it be contrary to the general custom---which, according to Augustine [*Ad Casulan. Ep. xxxvi], "has the force of law"---all this must be reckoned excessive and superstitious, because consisting, as it does, of mere externals, it has no connection with the internal worship of God. Hence Augustine (De Vera Relig. iii) quotes the words of Lc 17,21, "The kingdom of God is within you," against the "superstitious," those, to wit, who pay more attention to externals.

Reply to Objection: 1. The glorification of God implies that what is done is done for God's glory: and this excludes the excess denoted by superstition.
2. Faith, hope and charity subject the mind to God, so that there can be nothing excessive in them. It is different with external acts, which sometimes have no connection with these virtues.
3. This argument considers excess by way of absolute quantity.


We must now consider idolatry: under which head there are four points of inquiry:

(1) Whether idolatry is a species of superstition?

(2) Whether it is a sin?

(3) Whether it is the gravest sin?

(4) Of the cause of this sin.

Whether idolatry is rightly reckoned a species of superstition?

Objection: 1. It would seem that idolatry is not rightly reckoned a species of superstition. Just as heretics are unbelievers, so are idolaters. But heresy is a species of unbelief, as stated above (Question [11], Article [1]). Therefore idolatry is also a species of unbelief and not of superstition.
2. Further, latria pertains to the virtue of religion to which superstition is opposed. But latria, apparently, is univocally applied to idolatry and to that which belongs to the true religion. For just as we speak univocally of the desire of false happiness, and of the desire of true happiness, so too, seemingly, we speak univocally of the worship of false gods, which is called idolatry, and of the worship of the true God, which is the latria of true religion. Therefore idolatry is not a species of superstition.
3. Further, that which is nothing cannot be the species of any genus. But idolatry, apparently, is nothing: for the Apostle says (1Co 8,4): "We know that an idol is nothing in the world," and further on (1Co 10,19): "What then? Do I say that what is offered in sacrifice to idols is anything? Or that the idol is anything?" implying an answer in the negative. Now offering things to idols belongs properly to idolatry. Therefore since idolatry is like to nothing, it cannot be a species of superstition.
4. Further, it belongs to superstition to give divine honor to whom that honor is not due. Now divine honor is undue to idols, just as it is undue to other creatures, wherefore certain people are reproached (Rm 1,25) for that they "worshipped and served the creature rather than the Creator." Therefore this species of superstition is unfittingly called idolatry, and should rather be named "worship of creatures."

On the contrary It is related (Ac 17,16) that when Paul awaited Silas and Timothy at Athens, "his spirit was stirred within him seeing the whole city given to idolatry," and further on (Ac 17,22) he says: "Ye men of Athens, I perceive that in all things you are too superstitious." Therefore idolatry belongs to superstition.
I answer that As stated above (Question [92], Article [2]), it belongs to superstition to exceed the due mode of divine worship, and this is done chiefly when divine worship is given to whom it should not be given. Now it should be given to the most high uncreated God alone, as stated above (Question [81], Article [1]) when we were treating of religion. Therefore it is superstition to give worship to any creature whatsoever.Now just as this divine worship was given to sensible creatures by means of sensible signs, such as sacrifices, games, and the like, so too was it given to a creature represented by some sensible form or shape, which is called an "idol." Yet divine worship was given to idols in various ways. For some, by means of a nefarious art, constructed images which produced certain effects by the power of the demons: wherefore they deemed that the images themselves contained something God-like, and consequently that divine worship was due to them. This was the opinion of Hermes Trismegistus [*De Natura Deorum, ad Asclep], as Augustine states (De Civ. Dei viii, 23): while others gave divine worship not to the images, but to the creatures represented thereby. The Apostle alludes to both of these (Rm 1,23 Rm 1,25). For, as regards the former, he says: "They changed the glory of the incorruptible God into the likeness of the image of a corruptible man, and of birds, and of four-footed beasts, and of creeping things," and of the latter he says: "Who worshipped and served the creature rather than the Creator."These latter were of three ways of thinking. For some deemed certain men to have been gods, whom they worshipped in the images of those men: for instance, Jupiter, Mercury, and so forth. Others again deemed the whole world to be one god, not by reason of its material substance, but by reason of its soul, which they believed to be God, for they held God to be nothing else than a soul governing the world by movement and reason: even as a man is said to be wise in respect not of his body but of his soul. Hence they thought that divine worship ought to be given to the whole world and to all its parts, heaven, air, water, and to all such things: and to these they referred the names of their gods, as Varro asserted, and Augustine relates (De Civ. Dei vii, 5). Lastly, others, namely, the Platonists, said that there is one supreme god, the cause of all things. After him they placed certain spiritual substances created by the supreme god. These they called "gods," on account of their having a share of the godhead; but we call them "angels." After these they placed the souls of the heavenly bodies, and beneath these the demons which they stated to be certain animal denizens of the air, and beneath these again they placed human souls, which they believed to be taken up into the fellowship of the gods or of the demons by reason of the merit of their virtue. To all these they gave divine worship, as Augustine relates (De Civ . . Dei xviii, 14).The last two opinions were held to belong to "natural theology" which the philosophers gathered from their study of the world and taught in the schools: while the other, relating to the worship of men, was said to belong to "mythical theology" which was wont to be represented on the stage according to the fancies of poets. The remaining opinion relating to images was held to belong to "civil theology," which was celebrated by the pontiffs in the temples [*De Civ. Dei vi, 5].Now all these come under the head of the superstition of idolatry. Wherefore Augustine says (De Doctr. Christ. ii, 20): "Anything invented by man for making and worshipping idols, or for giving Divine worship to a creature or any part of a creature, is superstitious."

Reply to Objection: 1. Just as religion is not faith, but a confession of faith by outward signs, so superstition is a confession of unbelief by external worship. Such a confession is signified by the term idolatry, but not by the term heresy, which only means a false opinion. Therefore heresy is a species of unbelief, but idolatry is a species of superstition.
2. The term latria may be taken in two senses. In one sense it may denote a human act pertaining to the worship of God: and then its signification remains the same, to whomsoever it be shown, because, in this sense, the thing to which it is shown is not included in its definition. Taken thus latria is applied univocally, whether to true religion or to idolatry, just as the payment of a tax is univocally the same, whether it is paid to the true or to a false king. In another sense latria denotes the same as religion, and then, since it is a virtue, it is essential thereto that divine worship be given to whom it ought to be given; and in this way latria is applied equivocally to the latria of true religion, and to idolatry: just as prudence is applied equivocally to the prudence that is a virtue, and to that which is carnal.
3. The saying of the Apostle that "an idol is nothing in the world" means that those images which were called idols, were not animated, or possessed of a divine power, as Hermes maintained, as though they were composed of spirit and body. In the same sense we must understand the saying that "what is offered in sacrifice to idols is not anything," because by being thus sacrificed the sacrificial flesh acquired neither sanctification, as the Gentiles thought, nor uncleanness, as the Jews held.
4. It was owing to the general custom among the Gentiles of worshipping any kind of creature under the form of images that the term "idolatry" was used to signify any worship of a creature, even without the use of images.

Whether idolatry is a sin?

Objection: 1. It would seem that idolatry is not a sin. Nothing is a sin that the true faith employs in worshipping God. Now the true faith employs images for the divine worship: since both in the Tabernacle were there images of the cherubim, as related in Ex 25, and in the Church are images set up which the faithful worship. Therefore idolatry, whereby idols are worshipped, is not a sin.
2. Further, reverence should be paid to every superior. But the angels and the souls of the blessed are our superiors. Therefore it will be no sin to pay them reverence by worship, of sacrifices or the like.
3. Further, the most high God should be honored with an inward worship, according to Jn 4,24, "God . . . they must adore . . . in spirit and in truth": and Augustine says (Enchiridion iii), that "God is worshipped by faith, hope and charity." Now a man may happen to worship idols outwardly, and yet not wander from the true faith inwardly. Therefore it seems that we may worship idols outwardly without prejudice to the divine worship.

On the contrary It is written (Ex 20,5): "Thou shalt not adore them," i.e. outwardly, "nor serve them," i.e. inwardly, as a gloss explains it: and it is a question of graven things and images. Therefore it is a sin to worship idols whether outwardly or inwardly.
I answer that There has been a twofold error in this matter. For some [*The School of Plato] have thought that to offer sacrifices and other things pertaining to latria, not only to God but also to the others aforesaid, is due and good in itself, since they held that divine honor should be paid to every superior nature, as being nearer to God. But this is unreasonable. For though we ought to revere all superiors, yet the same reverence is not due to them all: and something special is due to the most high God Who excels all in a singular manner: and this is the worship of latria.Nor can it be said, as some have maintained, that "these visible sacrifices are fitting with regard to other gods, and that to the most high God, as being better than those others, better sacrifices, namely, the service of a pure mind, should be offered" [*Augustine, as quoted below]. The reason is that, as Augustine says (De Civ. Dei x, 19), "external sacrifices are signs of internal, just as audible words are signs of things. Wherefore, just as by prayer and praise we utter significant words to Him, and offer to Him in our hearts the things they signify, so too in our sacrifices we ought to realize that we should offer a visible sacrifice to no other than to Him Whose invisible sacrifice we ourselves should be in our hearts."Others held that the outward worship of latria should be given to idols, not as though it were something good or fitting in itself, but as being in harmony with the general custom. Thus Augustine (De Civ. Dei vi, 10) quotes Seneca as saying: "We shall adore," says he, "in such a way as to remember that our worship ss in accordance with custom rather than with the reality": and (De Vera Relig. v) Augustine says that "we must not seek religion from the philosophers, who accepted the same things for sacred, as did the people; and gave utterance in the schools to various and contrary opinions about the nature of their gods, and the sovereign good." This error was embraced also by certain heretics [*The Helcesaitae], who affirmed that it is not wrong for one who is seized in time of persecution to worship idols outwardly so long as he keeps the faith in his heart.But this is evidently false. For since outward worship is a sign of the inward worship, just as it is a wicked lie to affirm the contrary of what one holds inwardly of the true faith so too is it a wicked falsehood to pay outward worship to anything counter to the sentiments of one's heart. Wherefore Augustine condemns Seneca (De Civ. Dei vi, 10) in that "his worship of idols was so much the more infamous forasmuch as the things he did dishonestly were so done by him that the people believed him to act honestly."

Reply to Objection: 1. Neither in the Tabernacle or Temple of the Old Law, nor again now in the Church are images set up that the worship of latria may be paid to them, but for the purpose of signification, in order that belief in the excellence of angels and saints may be impressed and confirmed in the mind of man. It is different with the image of Christ, to which latria is due on account of His Divinity, as we shall state in the TP, Question [25], Article [3].
2. 3. The Replies to the Second and Third Objections are evident from what has been said above.

Whether idolatry is the gravest of sins?

Objection: 1. It would seem that idolatry is not the gravest of sins. The worst is opposed to the best (Ethic. viii, 10). But interior worship, which consists of faith, hope and charity, is better than external worship. Therefore unbelief, despair and hatred of God, which are opposed to internal worship, are graver sins than idolatry, which is opposed to external worship.
2. Further, the more a sin is against God the more grievous it is. Now, seemingly, a man acts more directly against God by blaspheming, or denying the faith, than by giving God's worship to another, which pertains to idolatry. Therefore blasphemy and denial of the faith are more grievous sins than idolatry.
3. Further, it seems that lesser evils are punished with greater evils. But the sin of idolatry was punished with the sin against nature, as stated in Rm 1,26. Therefore the sin against nature is a graver sin than idolatry.
4. Further, Augustine says (Contra Faust. xx, 5): "Neither do we say that you," viz. the Manichees, "are pagans, or a sect of pagans, but that you bear a certain likeness to them since you worship many gods: and yet you are much worse than they are, for they worship things that exist, but should not be worshiped as gods, whereas you worship things that exist not at all." Therefore the vice of heretical depravity is more grievous than idolatry.
5. Further, a gloss of Jerome on Ga 4,9, "How turn you again to the weak and needy elements?" says: "The observance of the Law, to which they were then addicted, was a sin almost equal to the worship of idols, to which they had been given before their conversion." Therefore idolatry is not the most grievous sin.

On the contrary A gloss on the saying of Lv 15,25, about the uncleanness of a woman suffering from an issue of blood, says: "Every sin is an uncleanness of the soul, but especially idolatry."
I answer that The gravity of a sin may be considered in two ways. First, on the part of the sin itself, and thus idolatry is the most grievous sin. For just as the most heinous crime in an earthly commonwealth would seem to be for a man to give royal honor to another than the true king, since, so far as he is concerned, he disturbs the whole order of the commonwealth, so, in sins that are committed against God, which indeed are the greater sins, the greatest of all seems to be for a man to give God's honor to a creature, since, so far as he is concerned, he sets up another God in the world, and lessens the divine sovereignty. Secondly, the gravity of a sin may be considered on the part of the sinner. Thus the sin of one that sins knowingly is said to be graver than the sin of one that sins through ignorance: and in this way nothing hinders heretics, if they knowingly corrupt the faith which they have received, from sinning more grievously than idolaters who sin through ignorance. Furthermore other sins may be more grievous on account of greater contempt on the part of the sinner.

Reply to Objection: 1. Idolatry presupposes internal unbelief, and to this it adds undue worship. But in a case of external idolatry without internal unbelief, there is an additional sin of falsehood, as stated above (Article [2]).
2. Idolatry includes a grievous blasphemy, inasmuch as it deprives God of the singleness of His dominion and denies the faith by deeds.
3. Since it is essential to punishment that it be against the will, a sin whereby another sin is punished needs to be more manifest, in order that it may make the man more hateful to himself and to others; but it need not be a more grievous sin: and in this way the sin against nature is less grievous than the sin of idolatry. But since it is more manifest, it is assigned as a fitting punishment of the sin of idolatry, in order that, as by idolatry man abuses the order of the divine honor, so by the sin against nature he may suffer confusion from the abuse of his own nature.
4. Even as to the genus of the sin, the Manichean heresy is more grievous than the sin of other idolaters, because it is more derogatory to the divine honor, since they set up two gods in opposition to one another, and hold many vain and fabulous fancies about God. It is different with other heretics, who confess their belief in one God and worship Him alone.
5. The observance of the Law during the time of grace is not quite equal to idolatry as to the genus of the sin, but almost equal, because both are species of pestiferous superstition.

Summa Th. II-II EN Qu.91 a.2