Act of Religion

A somewhat amusing passage from Aquinas's commentary on 1 Corinthians (section 329). But the phrasing is amusing only because we don't really talk about sex in this way any more, or at least not much. But there's something rather defective about a perspective on sex that can't conceive of it as a morally virtuous act, so joke's on us.

Hence it should be noted that the conjugal act is sometimes meritorious and without any mortal or venial sin, as when it is directed to the good of procreation and education of a child for the worship of God; for then it is an act of religion; or when it is performed for the sake of rendering the debt, it is an act of justice. But every virtuous act is meritorious, if it is performed with charity. But sometimes it is accompanied with venial sin, namely, when one is excited to the matrimonial act by concupiscence, which nevertheless stays within the limits of the marriage, namely, that he is content with his wife only. But sometimes it is performed with mortal sin, as when concupiscence is carried beyond the limits of the marriage; for example, when the husband approaches the wife with the idea that he would just as gladly or more gladly approach another woman. In the first way, therefore, the act of marriage requires no concession; in the second way it obtains a concession, inasmuch as someone consenting to concupiscence toward the wife is not guilty of mortal sin; in the third way there is absolutely no concession.