In accord with Scripture and Tradition, St. Thomas condemns homosexual acts as a type of unnatural sexual act termed ‘the unnatural vice’. This terminology, referring to homosexual acts as unnatural, is in accord with Sacred Scripture:
[Romans]
{1:26} Because of this, God handed them over to shameful passions. For example, their females have exchanged the natural use of the body for a use which is against nature.
{1:27} And similarly, the males also, abandoning the natural use of females, have burned in their desires for one another: males doing with males what is disgraceful, and receiving within themselves the recompense that necessarily results from their error.
{1:28} And since they did not prove to have God by knowledge, God handed them over to a morally depraved way of thinking, so that they might do those things which are not fitting:
The ‘natural use of the body’ to which Paul refers is that type of sexual act, between a man and a woman, that is inherently capable of procreation. The natural sexual act is inherently ordered toward procreation. If a couple is infertile due to injury, illness, or old age, the type of act remains inherently ordered toward the end of procreation, even though that end cannot be attained, and so the act remains natural and moral.
The ‘use which is against nature’ to which Paul refers is any type of sexual act that is not the natural type. In particular, in this passage, Paul condemns homosexual acts, sexual acts between persons of the same gender. Homosexual sexual acts, whether between two men or two women, are disgraceful and morally depraved; this type of sexual act is intrinsically evil and always gravely immoral.
But according to Saint Thomas Aquinas (Summa, II-II, 154), other types of acts are also correctly termed unnatural sexual acts:
“I answer that, As stated above (A6,9) wherever there occurs a special kind of deformity whereby the venereal act is rendered unbecoming, there is a determinate species of lust. This may occur in two ways: First, through being contrary to right reason, and this is common to all lustful vices; secondly, because, in addition, it is contrary to the natural order of the venereal act as becoming to the human race: and this is called “the unnatural vice.” This may happen in several ways. First, by procuring pollution [i.e. masturbation], without any copulation, for the sake of venereal pleasure: this pertains to the sin of “uncleanness” which some call “effeminacy.” Secondly, by copulation with a thing of undue species, and this is called “bestiality.” Thirdly, by copulation with an undue sex, male with male, or female with female, as the Apostle states (Romans 1:27): and this is called the “vice of sodomy.” Fourthly, by not observing the natural manner of copulation, either as to undue means, or as to other monstrous and bestial manners of copulation.”
Notice that unnatural sexual acts are not limited to homosexual acts (male with male, or female with female). The fourth type of unnatural sexual act listed by St. Thomas is between a man and a woman who do not observe the natural manner of copulation, in other words, they commit sexual acts such as manual, oral, or anal sex. These types of sexual acts are condemned unequivocally by St. Thomas as unnatural sexual acts; they are “monstrous and bestial manners of copulation.” The reference to use of unnatural sexual acts as an ‘undue means’ is a condemnation of unnatural sexual acts between a man and a woman as a type of foreplay. So even when the unnatural sexual act is a means to the good end of natural marital relations, the unnatural sexual act is gravely immoral. For the end does not justify the means.
St. Thomas reiterates this point later in the same article (12):
“Lastly comes the sin of not observing the right manner of copulation, which is more grievous if the abuse regards the “vas” than if it affects the manner of copulation in respect of other circumstances.”
The term ‘vas’ [Latin for vessel] refers to body parts. So the use of body parts not intended by God for procreation (hand, mouth, anus, etc.) in sexual acts, even between a husband and wife, is a grave sin. This type of act is one type of unnatural vice, substantially similar in moral species to homosexual acts, since both are unnatural.
St. Thomas goes on to answer other questions on the topic of homosexuality: “Article 12. Whether the unnatural vice is the greatest sin among the species of lust?” His answer is ‘Yes’, for “Augustine says … ‘of all these,’ namely the sins belonging to lust, ‘that which is against nature is the worst.’ ”
St. Thomas: “Therefore, since by the unnatural vices man transgresses that which has been determined by nature with regard to the use of venereal actions, it follows that in this matter this sin is gravest of all. After it comes incest, which, as stated above (Article 9), is contrary to the natural respect which we owe persons related to us.”
Homosexual acts are the worst type of sexual sin (based on the moral species, not on intention or circumstances), even worse than incest, adultery, prostitution, and other sexual sins.
St. Thomas: “Just as the ordering of right reason proceeds from man, so the order of nature is from God Himself: wherefore in sins contrary to nature, whereby the very order of nature is violated, an injury is done to God, the Author of nature. Hence Augustine says (Confess. iii, 8): ‘Those foul offenses that are against nature should be everywhere and at all times detested and punished, such as were those of the people of Sodom, which should all nations commit, they should all stand guilty of the same crime, by the law of God which hath not so made men that they should so abuse one another. For even that very intercourse which should be between God and us is violated, when that same nature, of which He is the Author, is polluted by the perversity of lust.’ “
Even the sin of sacrilege (which is committed, for example, as part of the sin of adultery, since all true marriages are ordained by God) is a lesser sin than homosexual acts:
“Vices against nature are also against God, as stated above (ad 1), and are so much more grievous than the depravity of sacrilege, as the order impressed on human nature is prior to and more firm than any subsequently established order.”
In fact, the only sexual sin that Saint Thomas Aquinas cites as worse than homosexual acts is bestiality:
St. Thomas: “Wherefore among sins against nature, the lowest place belongs to the sin of uncleanness, which consists in the mere omission of copulation with another. While the most grievous is the sin of bestiality, because use of the due species is not observed. Hence a gloss on Genesis 37:2, ‘He accused his brethren of a most wicked crime,’ says that ‘they copulated with cattle.’ After this comes the sin of sodomy, because use of the right sex is not observed.”
Sacred Scripture condemns homosexual acts (as I’ve discussed in previous posts) in many passages in both the Old Testament and the New Testament as “acts of grave depravity” (CCC, n. 2357; the footnote cites: Gen 191-29; Rom 124-27; 1 Cor 6:10; 1 Tim 1:10.).
But in addition, various passage of Scripture condemn even the homosexual orientation itself as a grave moral disorder. Certainly, sin is nothing else but a knowingly chosen immoral act. An orientation is not an act. But the homosexual orientation, while not per se a sin, is ordered toward gravely immoral sexual acts, and so it is a disorder of the human person pertaining to morality. And any interior consent to this orientation, that is to say, consent to desire for sexual relations between persons of the same gender, is not merely a disorder, but a gravely immoral interior act.
In my translation of Sacred Scripture, 2 Cor 12:21 condemns lust and fornication and homosexuality:
[2 Corinthians]
{12:21} If so, then, when I have arrived, God may again humble me among you. And so, I mourn for the many who sinned beforehand, and did not repent, over the lust and fornication and homosexuality, which they have committed.
This translation is in agreement with the Summa Theologica of Saint Thomas Aquinas:
“Article 11. Whether the unnatural vice is a species of lust?
“It is reckoned together with the other species of lust (2 Corinthians 12:21) where we read: ‘And have not done penance for the uncleanness, and fornication, and lasciviousness,’ where a gloss says: ‘Lasciviousness, i.e., unnatural lust.’ “
Unfortunately, most modern translations have obscured many of the passages that condemn homosexuality by interpreting certain words referring to homosexuality in an overly broad and general manner (e.g. as debauchery, or licentiousness, or even sensuality) so that the specific sin that is condemned cannot be perceived by the reader.
See my previous posts on this general topic:
Catholic teaching on homosexuality 1
Did Jesus approve of gay marriage? Not at all.
What effect do civil unions have on marriage?
Catholic teaching on homosexuality 2
Ronald L. Conte Jr.
Roman Catholic theologian and Bible translator
the reproach of Christ 