St. Thomas Aquinas on Rationalizing Sexual Hedonsim

For know you this and understand: that no fornicator or unclean or covetous person, which is a serving of idols, hath inheritance in the kingdom of Christ and of God. Let no man deceive you with vain words. For because of these things cometh the anger of God upon the children of despair. Be ye not therefore partakers with them. (Eph. 5:5–7)

The Apostle above forbade carnal sins (5:3); here he threatens them with the penalty of damnation that is inflicted on sinners. [...]

He states For know you this and understand, that is, be actually certain of it and not just habitually. “These things I write to you that you may know that you have eternal life; you who believe in the name of the Son of God” (1 Jn. 5:13). And what does he write? That no fornicator or unclean or covetous person, which is a serving of idols, hath inheritance in the kingdom of Christ and of God.

Notice that he calls covetousness idolatry, for idolatry happens when the honor due God alone is given to creatures. Now there is a twofold honor due God; we must establish him as the goal of our life and we must put our trust of reaching the goal in him. Hence, whoever places these ‘in creatures is guilty of idolatry. A covetous person commits this when he fixes his end in a created reality as well as putting all his trust in it. “Of their silver and their gold they have made idols to themselves, that they might perish” (Os. 8:4). This happens since, as Proverbs 11 (28) affirms: “He that trusteth in his riches shall fall.” [...]

Notice that only in reference to carnal vices does he teach them to avoid being deceived. For from the beginning men have rationalized to find reasons why fornication and other venereal sins were not really sins so that they might indulge their cupidity without restraint. Hence he states vain words since words that claim these are not sins and do not exclude one from the kingdom of God and of Christ are irrational. “Beware lest any man cheat you by prophecy and vain deceit” (Col. 2:8).”

He demonstrates that such men are deceivers and their words fallacious since, if carnal sins were not sins, they would not be punished by God; God is just and does not impose a penalty where there is no offense. But such acts are punished by God and therefore are sins. He proves the minor when he says For because of these things comes the anger of God, namely, on account of carnal sins, upon the children of despair. This is evident in the flood (Gen. 7), in what happened to the Sodomites (Gen. 19); and again, almost the whole tribe of Benjamin was destroyed on account of this (Jg. 19 & 20).

He says the children of despair because those who sin in this way despair of eternal life. If they acted this way and still hoped for eternal life, it would rather be presumption than hope, which is the certain expectation of obtaining future beatitude meritoriously.

---

Source: St. Thomas Aquinas, Commentary on St. Paul's Epistle to the Ephesians, trans. by Matthew L. Lamb (Albany, NY: Magis Books, 1966), Dominican House of Studies website, accessed Sept. 23, 2014, http://dhspriory.org/thomas/Eph5.htm#3, 5.3.