1. In the Sermon on the Mount Christ said: "Think not that I have come to abolish the Law and the prophets; I have come not to abolish them but to fulfill them" (Mt 5:17). In order to understand clearly what such a fulfillment consists of, he then passes on to each single commandment. He also refers to the one which says: "You shall not commit adultery." Our previous meditation aimed at showing in what way the correct content of this commandment, desired by God, was obscured by the numerous compromises in the particular legislation of Israel. The prophets point out such content in a very true way. In their teachings they often denounce the abandonment of the true God-Yahweh by the people, comparing it to adultery.
Hosea, not only with words, but (as it seems) also in his behavior, is anxious to reveal to us(1), that the people's betrayal is similar to that in marriage, or rather, even more, to adultery practiced as prostitution: "Go, take to yourself a wife of harlotry, and have children of harlotry, for the land commits great harlotry by forsaking the Lord" (Hos 1:2). The prophet heeds this command within himself and accepts it as coming from God-Yahweh: "The Lord said to me, 'Go again, love a woman who is beloved of a paramour and is an adulteress'" (Hos 3:1). Although Israel may be so unfaithful with regard to its God, like the wife who "went after her lovers and forgot me" (Hos 2:13), Yahweh never ceases to search for his spouse. He does not tire of waiting for her conversion and her return, confirming this attitude with the words and actions of the prophet: "In that day, says the Lord, you will call me, 'My Husband,' and no longer will you call me, 'My Ba'al.... I will betroth you to me forever; I will betroth you to me in righteousness and in justice, in steadfast love and mercy. I will betroth you to me in faithfulness, and you shall know the Lord" (Hos 2:16, 19-20). This fervent call to conversion of the unfaithful wife-consort goes hand in hand with the following threat: "That she put away harlotry from her face, and her adultery from between her breasts, lest I strip her naked and make her as in the day she was born" (Hos 2:4-5).
2. The unfaithful Israel-spouse was reminded of this image of the humiliating nudity of birth, by the prophet Ezekiel, and even within a wider sphere.(2) "...but you were cast out on the open field, for you were abhorred, on the day that you were born. And when I passed by you, and saw you weltering in your blood, I said to you in your blood, "Live, and grow like a plant in the field." And you grew and became tall and arrived at full maidenhood. Your breasts were formed, and your hair had grown, yet you were naked and bare. When I passed by you again and looked upon you, behold, you were at the age for love, and I spread my skirt over you, and covered your nakedness. I plighted my troth to you and entered into a covenant with you, says the Lord God, and you became mine.... And I put a ring on your nose, and earrings in your ears, and a beautiful crown upon your head. Thus you were decked with gold and silver, and your raiment was of fine linen, and silk and embroidered cloth.... And your renown went forth among the nations because of your beauty, for it was perfect through the splendor which I had bestowed upon you.... But you trusted in your beauty, and played the harlot because of your renown, and lavished your harlotries on any passerby.... How lovesick is your heart, says the Lord God, seeing you did all these things, the deeds of a brazen harlot, making your lofty place in every square. Yet you were not like a harlot, because you scorned hire. Adulterous wife, who receives strangers instead of her husband" (Ez 16:5-8, 12-15, 30-32).
3. The quotation is rather long. However, the text is so important that it was necessary to bring it up again. It expresses the analogy between adultery and idolatry in an especially strong and exhaustive way. The similarity between the two parts of the analogy consists in the covenant accompanied by love. Out of love, God-Yahweh settles the covenant with Israel—which is not worthy of it—and for him Israel becomes as a most affectionate, attentive, and generous spouse-consort is towards his own wife. In exchange for this love, which ever since the dawning of history accompanies the chosen people, Yahweh-Spouse receives numerous betrayals: "haughtiness"—here we have the cult of idols, in which "adultery" is committed by Israel-spouse. In the analysis we are carrying out here, the essential thing is the concept of adultery, as put forth by Ezekiel. However, it can be said that the situation as a whole, in which this concept is included (in the analogical sphere), is not typical. Here it is not so much a question of the mutual choice made by the husband and wife, which is born from mutual love, but of the choice of the wife (which was already made at the moment of her birth). This choice derives from the love of the husband, a love which on the part of the husband himself is an act of pure mercy. This choice is outlined in the following way. It corresponds to that part of the analogy which defines the covenant of Yahweh with Israel. But on the other hand, it corresponds to a lesser degree to the second part of it, which defines the nature of marriage. Certainly, the mentality of that time was not very sensitive to this reality—according to the Israelites, marriage was rather the result of a unilateral choice, often made by the parents—nevertheless, such a situation seldom forms part of our mentality.
4. Apart from this detail, we can note that the texts of the prophets have a different meaning of adultery from that given by the legislative tradition. Adultery is a sin because it constitutes the breakdown of the personal covenant between the man and the woman. In the legislative texts, the violation of and the right of ownership is pointed out, primarily the right of ownership of the man in regard to that woman who was his legal wife, one of many. In the text of the prophets, the background of real and legalized polygamy does not alter the ethical meaning of adultery. In many texts monogamy appears as the only correct analogy of monotheism as understood in the categories of the covenant, that is, of faithfulness and confidence toward the one true God-Yahweh, the Spouse of Israel. Adultery is the antithesis of that nuptial relationship. It is the antinomy of marriage (even as an institution) inasmuch as the monogamous marriage accomplishes within itself the interpersonal alliance of the man and the woman. It achieves the alliance born from love and received by both parties, precisely as marriage (and, as such, is recognized by society). This type of covenant between two people constitutes the foundation of that union when "man...cleaves to his wife and they become one flesh" (Gn 2:24). In the above-mentioned context, one can say that such bodily union is their "right" (bilateral). But above all, it is the regular sign of the communion of the two people, a union formed between the man and the woman in the capacity of husband and wife. Adultery committed by either one of them is not only the violation of this right, which is exclusive to the other marriage partner, but at the same time it is a radical falsification of this sign. It seems that in the pronouncements of the prophets, this aspect of adultery is expressed in a sufficiently clear manner.
5. Adultery is a falsification of that sign which does not have its "legality" so much as its simple interior truth in marriage—that is, in the cohabitation of the man and the woman who have become a married couple—then, in a certain sense, we refer again to the basic statements made previously, considering them essential and important for the theology of the body, from both an ethical and anthropological point of view. Adultery is a "sin of the body." The whole tradition of the Old Testament bears witness to it, and Christ confirms it. The comparative analysis of his words in the Sermon on the Mount (Mt 5:27-28), like the several relevant enunciations contained in the Gospels and in other parts of the New Testament, allows us to establish the exact reason for the sinfulness of adultery. It is obvious that we determine the reason for sinfulness, or rather for moral evil, basing ourselves on the principle of contraposition, in regard to that moral goodness which is faithfulness in marriage. That goodness can be adequately achieved only in the exclusive relationship of both parties (that is, in the marriage relationship between a man and a woman). Such a relationship needs precisely nuptial love. As we have already pointed out, the interpersonal structure of this love is governed by the interior "normativity" of the communion of the two people concerned. Precisely this gives a fundamental significance to the covenant (either in the relationship of man-woman, or, analogously, in the relationship of Yahweh-Israel). One can judge on the basis of the contraposition of the marriage pact as it is understood, with adultery, its sinfulness, and the moral evil contained in it.
6. All this must be kept in mind when we say that adultery is a sin of the body. The body is considered here in the conceptual bond with the words of Genesis 2:24. This speaks of the man and the woman, who, as husband and wife, unite so closely as to form "one body only." Adultery indicates an act through which a man and a woman, who are not husband and wife, unite as "one body only" (that is, those who are not husband and wife in a monogamous sense, as was originally established, rather than in the legal casuistic sense of the Old Testament). The sin of the body can be identified only in regard to the relationship between the people concerned. One can speak of moral good and evil according to whether in this relationship there is a true "union of the body" and whether or not it has the character of the truthful sign. In this case, we can therefore judge adultery as a sin, according to the objective content of the act.
This is the content which Christ had in mind when, in the Sermon on the Mount, he reminded us: "You have understood that it was said: 'You shall not commit adultery.'" However Christ did not dwell on such an aspect of the problem.
1) Cf. Hos 1-3
2) Cf. Ez 16:5-8, 12-15, 30-32
Source: L'Osservatore Romano