Lust, Fornication, and Adultery--What's the Difference?


Mat 5:27-28--"Ye have heard that it was said, Thou shalt not commit adultery: but I say unto you, that every one that looketh on a woman to lust after her hath committed adultery with her already in his heart."

Preachers and elders particularly are often asked "How's a person to know? When have I 'crossed the line' from just noticing that a woman has a nice smile or pretty hair or a nice figure and when I have lusted after her?" And the same church leaders are also asked "Has my mate crossed the line from 'just noticing' someone to actually being unfaithful? Is my husband's emotional unfaithfulness enough to be grounds for divorce?"


The presumption in this discussion is that the person doing the asking is of the mindset of trying to "abstain from all appearance of evil" (I Thessalonians 5: 22). If that's not the stance, this lesson will become an exercise in hair-splitting and legalism that may or may not hold up in the last Day. The last thing any elder or preacher would want to do is give someone the "all clear" sign for getting a divorce and then find out to his horror on Judgement Day that the opinion was wrong. Lust, fornication, and adultery are not casual topics. They have eternal consequences. We dare not be wrong.



Lust is an inordinate affection, a passion (according to Strong's concordance). It is "an intense desire that would throw off restraint" (Thayer). I John 2: 15-17 speaks of a lust of the flesh, a lust of the eyes, and the pride of life. Lust is more than just noticing that someone has a healthy figure or dimples. Lust is a desire so intense that it makes plans to set aside or break the ordinary rules of morality and to obtain the object of lust at almost any cost. "Good looks" create admiration, but lust makes plans. It makes plans to steal if the lust is a lust of the eyes. It makes plans for an illicit sexual union if the lust is a lust of the flesh. Lust makes plans for one to be alone with a person to whom he is or she is not married in order to experience the interactions that have been reserved by God for marriage (see Genesis 39: 10, Potiphar's wife, for but one example).


Sex in and of itself is pure, created by God to be enjoyed within the context of marriage (I Timothy 4: 1-5; Hebrews 13: 4, "the marriage bed is undefiled."). Sex is God's gift to married people. Desire for one's mate is holy (Genesis 3: 16 . . . and thy desire shall be to thy husband, and he shall rule over thee") and the Song of Solomon was written to help kindle the desire of husband for wife and wife for husband. It is not lust when the desire is for one's mate.

Fornication is the physical act of the sexual union between any two people that are not married to each other. One person can lust, but it takes two to fornicate. Fornication is heavily condemned in a host of passages (most of of the 20th chapter of Leviticus; Deutoronomy 22: 13-30; 23: Deuteronomy 23: 17, 18; I Corinthians 6: 9-11; Ephesians 5: 3-12; Colossians 3: 5; Galatains 5: 19; Revelation 21: 8; the King James, American Standard, and Revised Standard versions are most descriptive) in addition to the ones mentioned here. The distinction between fornication and adultery is that single people can fornicate, but it takes at least one of them being married for it to be adultery. Fornication is defined by the physical union--the becoming of one flesh (Genesis 2: 24). Fornication involves the acquisition of the forbidden knowledge (Genesis 4: 1, "Now Adam knew Eve his wife, and she conceived and bore Cain . . . ") of the other person. The knowledge involved in the Hebrew of the Old Testament is a very deep and personal knowledge, far beyond the "handshaking" awareness of another person. If we would live transformed lives that are above sin (Romans 12: 1,2), we should as Christians not seek to know those very personal things about people who are not our mates. But fornication takes people beyond those barriers.


To be the fornication that qualifies for severing a marriage, the physical act has to occur. Is "mental adultery" therefore sinless? No, Matthew 5: 27-28 again. But emotional or mental fornication is an individual sin and not one granting rights of divorce. Remember, the Jesus who said these things in Matthew 5: 27-28 is the same One who said in Mark 10:9 "What therefore God hath joined together, let not man put asunder." He is not the Jesus who authorized divorce for "mental cruelty" or "irreconcilable differences." For there to be one flesh (Matthew 19: 5), there has to be physical penetration, but the degree, duration, or saatisfaction by either party required is not defined anywhere by scripture. Perhaps the words of the Oklahoma legislation "Any degree of penetration, however slight, is sufficient to complete the crime" are in this instance a good description. When fornication has occurred and the innocent mate has proof, all of the options now belong to the innocent party.


It may be magnamous on the part of the innocent party to forgive a mate who has strayed (Matthew 18: 21-35) if he or she wants to, but where the marriage relationship is involved, scripture gives no requirement that forgiveness for adultery, as proven by fornication, be given. Fornication is declared to be a special sin in I Corinthians 6: 18. The innocent party can terminate the marriage the first time that proof positive occurs. It is at the moment of realization of a mate's unfaithfulness that a complete evaluation of the state of the marriage will be swift and unavoidable on the part of the innocent person. This is treacherous territory for couples to enter. They may not know their mates' innermost thoughts as well as they thought they did. The mate may have been waiting for an excuse for divorce and may be off and running for the courthouse the minute he or she hears about sex having occurred. The innocent party may divorce the sinful mate and re-marry ( Matthew 19: 9), no matter what the other considerations might be. The best advice is: don't fornicate. Don't even lust, because lust will lead toward fornication (compare James 1: 12-16). Lust, fornication, and adultery are all sins, and God hates sin.


If the innocent party does agree to forgive an instance of fornication, the forgiveness must be genuine. 1 Cor. 13:4-7 " Love suffereth long, and is kind; love envieth not; love vaunteth not itself, is not puffed up, doth not behave itself unseemly, seeketh not its own, is not provoked, taketh not account of evil; rejoiceth not in unrighteousness, but rejoiceth with the truth; beareth all things, believeth all things, hopeth all things, endureth all things." The sins that have been forgiven should not be brought up again and again as a club to beat a mate with, if the innocent mate decides to forgive and forget and start all over. The choice is to either forgive completely or go through with the divorce.

Adultery carries with it the idea of a mixing--in this case, the mixing of a pure relationship with an impure one (a third party to the marriage). In a less perjorative sense, the gold in much of our jewelry is adulterated because it is mixed with other metals to make the jewelry less breakable and more sturdy. Adultery as it applies to marriage has to do with taking on multiple mates, and the physical act of them becoming one flesh is fornication. God, the master designer, never designed marriage to be an institution with multiple mates or with mates of the same gender. Search your Bible; it just isn't there.


For marriages, adultery is pure poison. Adultery carries with it the idea of deception, of covenant-breaking, of cheating. Even in small amounts it can destroy a marriage. "Healthy adultery" is an oxymoron, two things in the same sentence or expression that cannot exist at the same time. Adultery is condemned by scripture (Matthew 19: 3-9; Mark 10: 2-12). It condemns people to Hell.. Time and time again, scripture uses "adultery" and "adulterous" as metaphors to describe unfaithful people who will not be going to Heaven. Stay away from these sins.


It should be noted that the sins reviewed here include the scriptures that describe the minimal standards for failure. These scriptures describe marriages and spiritual lives that are dead or almost dead. A woman will not be regarded as a great example of Christian womanhood if the best she seems to be able to do is avoid penetration by miscellaneous males while she flirts outrageously. A man will by no means become a great Sunday school teacher, preacher, deacon, or elder if he views pornography, stopping only before calling or emailing the people depicted to arrange for trysts. The "abundant life" (John 10: 10) and the peace that passes all understanding (Philippians 4: 4-9) are so very far above these standards. Rather this page was designed to help those who are trying to answer the question "Is my marriage truly dead?"


Click here to return to

the sermon index file.