Whether it is a mortal sin to have intercourse with a concubine?
Objection 1: It would seem that it is not a mortal sin to have intercourse with a concubine. For a lie is a greater sin than simple fornication: and a proof of this is that Juda, who did not abhor to commit fornication with Thamar, recoiled from telling a lie, saying (Gn. 38:23): "Surely she cannot charge us with a lie." But a lie is not always a mortal sin. Neither therefore is simple fornication.
Objection 2: Further, a deadly sin should be punished with death. But the Old Law did not punish with death intercourse with a concubine, save in a certain case (Dt. 22:25). Therefore it is not a deadly sin.
Objection 3: Further, according to Gregory (Moral. xxxiii, 12), the sins of the flesh are less blameworthy than spiritual sins. Now pride and covetousness, which are spiritual sins, are not always mortal sins. Therefore fornication, which is a sin of the flesh, is not always a mortal sin.
Objection 4: Further, where the incentive is greater the sin is less grievous, because he sins more who is overcome by a lighter temptation. But concupiscence is the greatest incentive to lust. Therefore since lustful actions are not always mortal sins, neither is simple fornication a mortal sin.
On the contrary, Nothing but mortal sin excludes from the kingdom of God. But fornicators are excluded from the kingdom of God (1 Cor. 6:9,10). Therefore simple fornication is a mortal sin.
Further, mortal sins alone are called crimes. Now all fornication is a crime according to Tob. 4:13, "Take heed to keep thyself . . . from all fornication, and beside thy wife never endure to know crime." Therefore, etc.
I answer that, As we have already stated (Sent. ii, D, 42, Q 1, A 4), those sins are mortal in their genus which violate the bond of friendship between man and God, and between man and man; for such sins are against the two precepts of charity which is the life of the soul. Wherefore since the intercourse of fornication destroys the due relations of the parent with the offspring that is nature's aim in sexual intercourse, there can be no doubt that simple fornication by its very nature is a mortal sin even though there were no written law.
Reply to Objection 1: It often happens that a man who does not avoid a mortal sin, avoids a venial sin to which he has not so great an incentive. Thus, too, Juda avoided a lie while he avoided not fornication. Nevertheless that would have been a pernicious lie, for it would have involved an injury if he had not kept his promise.
Reply to Objection 2: A sin is called deadly, not because it is punished with temporal, but because it is punished with eternal death. Hence also theft, which is a mortal sin, and many other sins are sometimes not punished with temporal death by the law. The same applies to fornication.
Reply to Objection 3: Just as not every movement of pride is a mortal sin, so neither is every movement of lust, because the first movements of lust and the like are venial sins, even sometimes marriage intercourse. Nevertheless some acts of lust are mortal sins, while some movements of pride are venial: since the words quoted from Gregory are to be understood as comparing vices in their genus and not in their particular acts.
Reply to Objection 4: A circumstance is the more effective in aggravating a sin according as it comes nearer to the nature of sin. Hence although fornication is less grave on account of the greatness of its incentive, yet on account of the matter about which it is, it has a greater gravity than immoderate eating, because it is about those things which tighten the bond of human fellowship, as stated above. Hence the argument does not prove.
Supp. · Q. 65, Art. 5: Whether it was ever lawful to have a concubine?
Whether it was ever lawful to have a concubine?
Objection 1: It would seem that it has been sometimes lawful to have a concubine. For just as the natural law requires a man to have but one wife, so does it forbid him to have a concubine. Yet at times it has been lawful to have several wives. Therefore it has also been lawful to have a concubine.
Objection 2: Further, a woman cannot be at the same time a slave and a wife; wherefore according to the Law (Dt. 21:11, seqq.) a bondswoman gained her freedom by the very fact of being taken in marriage. Now we read that certain men who were most beloved of God, for instance Abraham and Jacob, had intercourse with their bondswomen. Therefore these were not wives, and consequently it was sometime lawful to have a concubine.
Objection 3: Further, a woman who is taken in marriage cannot be cast out, and her son should have a share in the inheritance. Yet Abraham sent Agar away, and her son was not his heir (Gn. 21:14). Therefore she was not Abraham's wife.
On the contrary, Things opposed to the precepts of the decalogue were never lawful. Now to have a concubine is against a precept of the decalogue, namely, "Thou shalt not commit adultery." Therefore it was never lawful.
Further, Ambrose says in his book on the patriarchs (De Abraham i, 4): "What is unlawful to a wife is unlawful to a husband." But it is never lawful for a wife to put aside her own husband and have intercourse with another man. Therefore it was never lawful for a husband to have a concubine.
I answer that, Rabbi Moses says (Doc. Perp. iii, 49) that before the time of the Law fornication was not a sin; and he proved his assertion from the fact that Juda had intercourse with Thamar. But this argument is not conclusive. For there is no need to excuse Jacob's sons from mortal sin, since they were accused to their father of a most wicked crime (Gn. 37:2), and consented kill Joseph and to sell him. Wherefore we must say that since it is against the natural law to have a concubine outside wedlock, as stated above (A 3), it was never lawful either in itself or by dispensation. For as we have shown (Doc. Perp. iii, 49) intercourse with a woman outside wedlock is an action improportionate to the good of the offspring which is the principal end of marriage: and consequently it is against the first precepts of the natural law which admit of no dispensation. Hence wherever in the Old Testament we read of concubines being taken by such men as we ought to excuse from mortal sin, we must needs understand them to have been taken in marriage, and yet to have been called concubines, because they had something of the character of a wife and something of the character of a concubine. In so far as marriage is directed to its principal end, which is the good of the offspring, the union of wife and husband is indissoluble or at least of a lasting nature, as shown above (A 1), and in regard to this there is no dispensation. But in regard to the secondary end, which is the management of the household and community of works, the wife is united to the husband as his mate: and this was lacking in those who were known as concubines. For in this respect a dispensation was possible, since it is the secondary end of marriage. And from this point of view they bore some resemblance to concubines, and for this reason they were known as such.
Reply to Objection 1: As stated above (A 1, ad 7,8) to have several wives is not against the first precepts of the natural law, as it is to have a concubine; wherefore the argument does not prove.
Reply to Objection 2: The patriarchs of old by virtue of the dispensation which allowed them several wives, approached their bondswomen with the disposition of a husband towards his wife. For these women were wives as to the principal and first end of marriage, but not as to the other union which regards the secondary end, to which bondage is opposed since a woman cannot be at once mate and slave.
Reply to Objection 3: As in the Mosaic law it was allowable by dispensation to grant a bill of divorce in order to avoid wife-murder (as we shall state further on, Q 67, A 6), so by the same dispensation Abraham was allowed to send Agar away, in order to signify the mystery which the Apostle explains (Gal. 4:22, seqq.). Again, that this son did not inherit belongs to the mystery, as explained in the same place. Even so Esau, the son of a free woman, did not inherit (Rom. 9:13, seqq.). In like manner on account of the mystery it came about that the sons of Jacob born of bond and free women inherited, as Augustine says (Tract. xi in Joan.) because "sons and heirs are born to Christ both of good ministers denoted by the free woman and of evil ministers denoted by the bondswoman."