Is “Lust” the Equivalent of “Fornication”?

By Wayne Jackson

The word “fornication” derives from the Greek term porneia, one of a cognate group of five words that together occur fifty-five times in the New Testament. The noun form is found twenty-five times, predominately in the letters of Paul. The word is generic in scope in that it refers to a variety of physical sexual acts between persons who are not married legitimately. It will be the goal of this article to establish that when fornication, and a related term, “adultery” (moicheia), are used literally, they are physical acts that constitute the exclusive rationale for divorce and possible remarriage.
In the Greek version of the Old Testament (LXX), a form of porneia is used of Tamar, with whom Judah had engaged in intercourse, having assumed that she was a “harlot” (Genesis 38:15; cf. v. 24). In ancient Babylon it was believed that sexual intercourse ensured crop fertility. Herodotus, the Greek historian, tells of the yearly requirement of all women to sacrifice their bodies in “fornication” to a stranger in the temple of the goddess Mylitta (Rawlinson 1952, 1.199).
Mostly in the Old Testament, however, the terms “fornication” and “adultery” are employed symbolically of the actions of the Israelite people who broke their “marriage covenant” with Jehovah by worshipping idols (cf. Ezekiel 16:26,29; Hosea 1:2).
Sexual union with a married person (with whom one has no right to intimacy) is both fornication and adultery (cf. 1 Corinthians 5:1). All adultery is also fornication; not all fornication is adultery (cf. 1 Corinthians 7:2). The technical difference between fornication and adultery is implied in sin lists, in which both terms are included (cf. 1 Corinthians 6:9).
Specifically then, fornication is any “unlawful sexual intercourse” (Danker and Bauer 2000, 854), whether such is a man-woman liaison, a homosexual action (cf. Jude 7), pedophilia, or sex-for-hire, as in prostitution (Brown 1975, 497). The plural form, “fornications” (1 Corinthians 7:2), hints of the various venues by which this horrible sin may be committed.
I must add this point. Bible translations that render porneia more generically (e.g., “sexual immorality”) are misleading. There are various forms of sexual immorality (e.g., exposing one’s body in seductive clothing) that do not fall under the definition of fornication, though clearly they are sinful.

Is “Lust” Fornication?

Rather recently, some have alleged that “lust” falls into the category of fornication/adultery. If, therefore, a married person should discover that a spouse has read a book or viewed pictures/films containing explicit sexual activity, the assumption is that the offender has lusted, hence has committed adultery—even if there has been no physical contact with another person. Therefore, the transgressor may be justly divorced according to Matthew 5:27-28; the innocent victim would then have the option to remarry. The text reads as follows:

You have heard that it was said, “You shall not commit adultery”: but I say unto you, that every one who looks on a woman to lust after her has committed adultery with her already in his heart.

A brief analysis of the passage is in order.
Christ quoted from the Ten Commandments, “You shall not commit adultery” (Exodus 20:14). Clearly this refers to a physical sex act by which one violates a marriage relationship. But the Savior expands the moral lapse by addressing the mental disposition that lends itself to the overt physical act.
He speaks of the man who longingly looks (the verb is a present tense form) at someone other than his spouse — with a sustained desire for intercourse. This is no passing glance. The lusting person is doing mentally what he (or she) almost certainly would do physically, if given the opportunity. One scholar notes:

Christians must recognize those thoughts and actions which, long before any overt sexual sin, make the possibility of giving in to temptation more likely, and they must take dramatic action to avoid them (Blomberg 1992, 109; emphasis added).

A “heart” sin is serious, but it does not have the equivalent temporal consequence the physical act does. Professor Robert Mounce observed that “the act of adultery” has “far more serious social consequences” (e.g., death under the Mosaic system — Leviticus 20:10) than lust, though both the desire and the act are sinful (1991, 46). Lust is of “the same nature” as the act, but it is not the act itself (Nixon 1970, 823). F.F. Bruce expressed the obvious, when he noted that “unchaste thought” is “enforceable by no earthly code or court” (1977, 25).
One additional note is worthy of consideration. Some scholars contend that it is grammatically possible that the phrase usually rendered “to lust after her” might carry the sense of “so as to get her to lust” (Carson 1984, 151; Blomberg 1992, 108-109). This would place a heavy responsibility upon one who provokes lust, as well as the person who indulges in such. Where does this leave the woman who seeks a divorce on the ground of lust, yet she herself flaunts her semi-nude body on the beach? Certainly without credibility, to say nothing of a flawed exegesis.
In view of the foregoing factors, we raise the crucial question again. Is the “lust” of Matthew 5:28 the consequential equivalent of the physical act of adultery, thus a cause for divorce and remarriage on the part of an innocent victim? We believe the answer is a firm “No.” The fallacy of this position can be demonstrated rather persuasively.

The Consequence of the “Lust = Fornication” Argument

1) In the immediate context Christ made a comparison between anger and murder (5:21-22), just as he did with lust and adultery. J.A. Alexander noted that the principles involved in the two situations are “identical” (1861, 141). If the reasoning reflected in the theory sketched above were valid, would it not be the case that both the murderer and the one merely angry with his brother should be subjected to the same temporal penalty (e.g., execution or imprisonment) by the legal authorities? Elsewhere the New Testament also declares that “hate” of one’s brother, in some sense, is the equivalent of “murder” (1 John 3:15), but no one contends that hate has the same legal ramification.
2) If the term “adultery” is to be pressed literally in Matthew 5:28, should the remedy that is subsequently imposed (i.e., the plucking out of the eye and the amputation of one’s hand) likewise be pressed literally? Clearly Christ is dealing with mental acts that, as evil as they are, do not yet rise to the level of physical murder or adultery, but are, in principle, serious sins. Certainly there is a nexus between what goes on in the heart, and what becomes manifest in physical actions (cf. Mark 7:21-23). Lust, when it “conceives,” bears sin (James 1:15), i.e., sin of a greater consequential nature.
3) If one of the persons in this lust/adultery scenario entertains impure thoughts, and the object of that lust acted in such a way as to cause the lust, would not logic suggest that the mates of both parties — the one lusting, and the accessory to the act — would have the right of divorce and remarriage? Can the serious Bible student not see that this throws the divorce/marriage controversy into a maze of confusion as folks attempt to decipher the mental states and levels of culpability of the alleged transgressors?

Matthew 19:9

The use of salacious literature/films, etc., within any context is evil. But this type of perversion most likely falls under the category of lasciviousness, a “comprehensive term” that can embrace various sexual aberrations (see Thayer 1958, 79-80; Balz and Schneider 1990, 169). The use of pornography certainly can constitute “adultery” in the heart. However, that is not what Jesus had in view as a basis for divorce in Matthew 19:9. In that context Christ unquestionably had in mind the physical act of sexual intercourse as evidenced by the fact: (a) that he had just spoken of the man and woman becoming “one flesh” in marriage; and (b) he subsequently spoke of the “eunuch” status.
A fundamental principle of Bible interpretation is that words must be interpreted literally unless there is a compelling reason for assigning to them a figurative meaning. The term “adultery” is not employed in a metaphorical sense in Matthew 19:9. In Matthew 5:28, however, “heart” adultery is a metaphor for evil desire (Danker et al. 2000, 509; cf. Romans 1:24).
Here is another example. “Friendship” with the world, in one sense, can be viewed as “adultery” (cf. James 4:4), but mere worldliness is not a cause for divorce and remarriage. Suppose a woman should claim: “My husband is a very worldly man. He gets drunk and gambles away his money. Friendship with the world is ‘adultery.’ Therefore, I have just grounds for a divorce and remarriage.” Can we not see that the lady has pressed “adultery” into a mold never intended by the sacred writer? It is a mistake to take a figurative use of the word “adultery,” and import it into a text that discusses a literal relationship.
If one were to frame the type of argument as that just under review with reference to Matthew 5:28, and press metaphorical language into literalism, he would be forced to contend that the person who fornicates with a prostitute, and thus has become “one” with her in that act (1 Corinthians 6:16), is “married to” the immoral person, and must remain in that union. Incredibly, a few inept students have attempted to sustain this ludicrous position! But such is absolutely untenable.
It is a serious interpretative mistake to force a literal meaning upon an expression that obviously is used figuratively. I have discussed and demonstrated this fallacy extensively in my book, Biblical Figures of Speech.