What does the Bible say about Fornication?                                             By Jack Kettler


As in previous studies, we will look at definitions, scriptures, lexical, and commentary evidence for the purpose to glorify God in how we live. Unfortunately, among young people today in nondenominational evangelistic churches, biblical reasons from abstaining for sex before marriage are said to be unclear.


Doctrinal uncertainty like this is shocking in light of the numerous warnings in Scripture about sexual immorality. How many of those saying such a thing have read the New Testament in its entirety? The problem is not with biblical clarity on this issue but with willful biblical illiteracy. Biblical ignorance is not an excuse that will work on judgment day.      


The Scriptures:


“Thou shalt not covet thy neighbor’s house; thou shalt not covet thy neighbor’s wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbor’s.” (Exodus 20:17)

“But I say unto you, that whosoever looketh on a woman to lust after her hath committed adultery (ἐμοίχευσεν emoicheusen) with her already in his heart.” (Matthew 5:28)

“For out of the heart proceed evil thoughts, murders, adulteries (μοιχεῖαι moicheiai), sexual immorality (πορνεῖαι porneiai), thefts, false witness, and blasphemies.” (Matthew 15:19)

“Flee fornication (πορνείαν porneian). Every sin that a man doeth is without the body; but he that committeth fornication (πορνεύων porneuōn) sinneth against his own body.” (1Corinthians 6:18)

“Now the works of the flesh are manifest, which are these; Adultery, fornication (Πορνεία Porneia), uncleanness, lasciviousness.” (Galatians 5:19)

“But sexual immorality (Πορνεία Porneia), and all uncleanness, or covetousness, let it not be once named among you, as becometh saints.” (Ephesians 5:3)

“Put to death therefore what is earthly in you: sexual immorality (πορνείαν porneian), impurity, passion, evil desire, and covetousness, which is idolatry.” (Colossians 3:5)

Glossary of terms and entries from Strong’s Lexicon:

Definition of fornication: Fornication is voluntary sexual intercourse between two people not married to each other. In contemporary usage, the term is often replaced with extramarital sex.

Fornication πορνείαν (porneian) Strong's Greek 4202: Fornication, whoredom, met: idolatry. From porneuo; harlotry; figuratively, idolatry.

Definition of adultery: Voluntary sexual intercourse between a married person and someone other than that person's current spouse.

Adultery ἐμοίχευσεν (emoicheusen) Strong's Greek 3431: To commit adultery (of a man with a married woman, but also of a married man). From moichos, to commit adultery.

Definition of sexual immorality:

Sexual immorality comes from the Greek word porneia. Porneia can also be translated as “whoredom,” “fornication,” and “idolatry.” It is primarily used of premarital sex. It can include adultery, prostitution, sexual relations between unmarried individuals, and homosexuality

Sexual immorality Πορνεία (Porneia) Strong's Greek 4202: Fornication, whoredom, met: idolatry. From porneuo; harlotry; figuratively, idolatry.

Synonyms for fornication:

Adultery, illicit intercourse, unlicensed intercourse, promiscuousness, extramarital sex, premarital sex, carnality, unchastely, lewdness, licentiousness, unfaithfulness, whoredom, harlotry, prostitution, and concubinage.

Clarifying comments:

Fornication refers to sexual relations outside of marriage whereas; the term sexual immorality is broader and covers many illicit sexual practices. Whenever the Scriptures call believers to flee from sexual immorality, it includes premarital sex.     

The Scriptures tell believers to “flee,” to “put to death,” and speaking of sexual sins, “let it not be once named among you.” The apostle Paul calls sexual sins “the works of the flesh” in Galatians 5:19. Paul clearly says, “For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live” (Romans 8:13).

Fornication, Fornicator - Vine's Expository Dictionary of New Testament Words

Fornication, Fornicator

[A-1, Noun, G4202, porneia]

is used

(a) of illicit sexual intercourse, in John 8:41; Acts 15:20, Acts 15:29; Acts 21:25; 1Corinthians 5:1; 1Corinthians 6:13, 1Corinthians 6:18; 2Corinthians 12:21; Galatians 5:19; Ephesians 5:3; Colossians 3:5; 1 Thessalonians 4:3; Revelation 2:21; Revelation 9:21; in the plural in 1 Corinthians 7:2; in Matthew 5:32; Matthew 19:9 it stands for, or includes, adultery; it is distinguished from it in Matthew 15:19; Mark 7:21;

(b) metaphorically, of “the association of pagan idolatry with doctrines of, and professed adherence to, the Christian faith,” Revelation 14:8; Revelation 17:2, Revelation 17:4; Revelation 18:3; Revelation 19:2; some suggest this as the sense in Revelation 2:21.

[A-2, Noun, G4205, pornos]

denotes “a man who indulges in fornication, a fornicator,” 1Corinthians 5:9-11; 1Corinthians 6:9; Ephesians 5:5, RV; 1Timothy 1:10, RV; Hebrews 12:16; Hebrews 13:4, RV; Revelation 21:8; Revelation 22:15, RV (AV, “whoremonger”).

[B-1, Verb, G4203, porneuo]

“to commit fornication,” is used

(a) literally, Mark 10:19; 1 Corinthians 6:18; 1 Corinthians 10:8; Revelation 2:14, Revelation 2:20, See

(a) and

(b) above;

(b) metaphorically, Revelation 17:2; Revelation 18:3, Revelation 18:9.

[B-2, Verb, G1608, ekporneuo]

a strengthened form of No. 1 (ek, used intensively), “to give oneself up to fornication,” implying excessive indulgence, Jude 1:7. (1)

Now for an outstanding overview of sexual immorality!

Baker's Evangelical Dictionary of Biblical Theology - Immorality, Sexual:

Immorality, Sexual

Interpersonal activity involving sex organs that does not conform to God's revealed laws governing sexuality. The account of creation (Gen 1:1-28) includes reproductive activity as an essential part of the developmental scheme. This important function is given special prominence in the narrative describing the creation of woman (Gen 2:21-24). In a process cloaked in mystery, God takes an aspect (Heb. sela, improperly translated “rib” in many versions) of Adam and fashions it into a genetic counterpart that is specifically female, and which matches Adam's maleness for purposes of reproducing the species. Adam and Eve are thus equal and complementary to one another, of the same physical and genetic composition apart from the slight difference that governs the characteristic nature of male and female fetuses. God tells them to “Be fruitful and increase in number; fill all the earth and subdue it” (Gen 1:28).

In normal males, the sex drive is a powerful biological and emotional force that is often difficult to control satisfactorily, particularly when it expresses itself in aggressive terms. But in the early narratives dealing with human family life there are no specific regulations for sexual behavior apart from the statement that Eve's husband will be the object of her carnal desires (Gen 3:16). As the world's population grows, so do the human misdemeanors (Gen 6:5-6), which seem to include mixed marriages (Gen 6:2) and possible sexual perversions, although the latter are not mentioned explicitly. At the same time there are certain situations of a sexual nature that are to be avoided by followers of the Lord. The shame associated with the exposure of male genitalia and the penalties that might accrue to observers (Gen 19:22-25) illustrates one form of prohibited sex-related activity. This represents the beginning of later Jewish traditions that held that nakedness was shameful.

In the patriarchal age, homosexuality was a prominent part of Canaanite culture, as the incident involving Lot in Sodom illustrates (Gen 19:1-9). So rampant was sexual perversion in that place that in later times the name of the city became synonymous with homosexual behavior. God's judgment upon such a perversion of sexuality was to destroy the city and its corrupt inhabitants.

When God entered into a covenant relationship with the Israelites on Mount Sinai (Exod. 24:1-11), his intent was to assemble and foster a select group of human beings who would be obedient to him, worship him as their one and only true God, and live under his direction in community as a priestly kingdom and a holy nation (Exod. 19:6). Holiness demands adherence to certain stringent rules regarding worship and general conduct, but also requires a complete commitment of will and motive to the Lord's commandments.

Because of the gross promiscuity of surrounding nations, whose behavior the Israelites are warned periodically to avoid, the covenant Lord reveals through Moses a collection of strict regulations that are to govern Israelite sexuality and morality. If these directives are followed, the individual and the community alike can expect blessing. But if the Israelites lapse into the immoral ways of nations such as Egypt and Canaan, they will be punished. God's keen interest in the sexuality of his chosen people has two objectives: to exhibit Israel to the world as a people fulfilling his standards of holiness, and to ensure that, in the process, they enjoy physical, mental, and moral health.

The pronouncements on sexuality given to Moses while the Israelites are encamped at Mount Sinai occur in two separate places in Leviticus (18:6-23; 20:10-21). It should be remembered that Leviticus (the "Levite" book) comprises a technical priestly manual dealing with regulations governing Israelite worship and the holiness of the covenant community. God had chosen the covenant nation to be an illustration to pagan society of how individuals can become as holy as God through implicit faith in him and continuous obedience to his commandments. By setting out guidelines for the priests to teach to the Israelites, God promulgates explicitly a catalog of what is, and is not, acceptable social, moral, and spiritual behavior. In the distinctions between clean and unclean that occur in various parts of the priestly handbook, the emphasis is on that purity of life that should characterize God's people. Enactments of this kind are unique in the ancient world, and only serve to demonstrate the seriousness of God's intent to foster a people that can indeed have spiritual fellowship with their Lord because they reflect his holy and pure nature as they walk in the way of his commandments.

A closer look must now be taken at the regulations governing sexuality. In Leviticus 18:6-23, the matter is approached by the use of denunciations to describe immoral behavior. These fall into two groups, one dealing with carnal associations among people closely related by blood (consanguinity), and the other governing the sexual behavior of persons related through marriage (affinity). Accordingly a man is prohibited from copulating with his mother or any other wife belonging to his father; a sister or half-sister, a daughter-in-law or a granddaughter, an aunt on either side of the family, a woman and her daughter or her son's daughter or daughter's daughter, a wife's sister as a rival wife, a neighbor's wife, and a woman during the menses. Homosexuality is castigated as reprehensible morally, and bestiality is condemned summarily. Everything forbidden had already led to the moral defilement of the nations surrounding Israel, and for these perversions they are to fall under divine judgment (v. 24).

Homosexuality is described in the Mosaic legislation in terms of a man lying with a man “as one lies with a woman” (Lev. 18:22; 20:13), that is, for purposes of sexual intercourse. The practice originated in humanity's remote past, and appears to have formed part of Babylonian religious activities. The Canaanites regarded their male and female cultic prostitutes as “holy persons,” meaning that they were dedicated specifically to the service of a god or goddess, not that they were exemplars of moral purity in society. While general condemnations of homosexuality occur in Leviticus, none of the pagan Near Eastern religions thought it either necessary or desirable to enact comparable legislation, since for them such activities were all part of normal religious life in temples or other places of cultic worship.

In general, homosexuality in Mesopotamia is not documented to any extent in surviving tablets, but that it was a widespread problem in the Middle Assyrian period (1300-900b.c.) is indicated by the fact that legislation from that time stipulates that an offender, when caught, should be castrated. This judicial sentence, when compared with the Hebrew prescription of death (Lev 20:13), shows that in Mesopotamian society the offense was regarded as a secondary civic infraction. While homosexuality seems to have been a recognized part of Hittite life, their laws nevertheless prescribe execution for a man who sodomizes his son.

Hebrew tradition, in contrast, is emphatic in condemning homosexuality, even though some Israelites succumbed to it. In Deuteronomy 23:18, male cultic prostitutes, and perhaps homosexuals also, are castigated as “dogs,” which is most probably the significance of the term in Revelation 22:15. Since the dog was generally despised by the Hebrews as an unclean animal, serving much the same scavenging purpose as the vulture (1Kings 22:38), the disparaging nature of the allusion is evident.

Bestiality, defined in terms of a man or woman having sexual relations with an animal (Lev 18:23; 20:15-16), is stigmatized in the Mosaic enactments as a defilement for a man and a sexual perversion for a woman. It appears to have been fairly common in antiquity (Lev 18:24), being indulged in by the Mesopotamians, Egyptians, and Hittites.

The shorter list of prohibited relationships in Leviticus 20:10-21 deals with many of the same offenses, but also prescribes punishments for such violations of Israel's moral code. Thus a man who commits adultery with his neighbor's wife is to be executed, along with his sexual partner. This is also the penalty for a man who defiles his father's wife or his daughter-in-law, because such activity constitutes sexual perversion as defined by God's laws. Homosexuality is once again condemned, and the sexual perverts sentenced to death. The marriage of a man, a woman, and her mother is deemed wicked, and the offenders sentenced to be burned with fire so as to expunge completely the wickedness of the act from the holy community. Bestiality, condemned already as a perversion, is regarded as a capital offense, which includes the animal also.

The marriage of a man with his sister from either side of the family is declared a highly immoral union, and the participants are to be put to death. The same is true of a man and a woman engaging in sexual activity during the woman's menstrual period. Such blood is considered highly defiling, and a gross violation of the purity that God desires as the norm for Israel's social behavior. The seriousness with which God assesses his holiness is reflected in the severe penalties prescribed for the infractions listed above. The phrase "their blood will be on their own heads" is a euphemism for capital punishment. Sexual relations between a man and his aunt, or between a man and his brother's wife, are regarded as dishonoring the legal spouses, and are accorded the lesser sentence of childlessness. In some cases, however, this is tantamount to causing the death of the family, a prospect that few Hebrews could contemplate with equanimity. In Deuteronomy 25:5-10, the law allows a man to marry his deceased brother's childless wife so as to rear a son for his brother's family, but this is very different from a man marrying his brother's wife while her legal husband is still alive.

There are important reasons why these enactments were part of ancient Hebrew law. Moral purity and spiritual dedication were fundamental requisites if the chosen people were to maintain their distinctive witness to God's power and holiness in society. The prohibitions reinforced the traditional emphasis on family honor, since the family was the building block of society. It had to be maintained at all costs if society was to survive. Any marriage relationship that was too close would have exerted a devastating effect on community solidarity by provoking family feuds that could last for centuries.

Serious problems would also have arisen through inter marriage when the result of such unions was the concentration of lands and riches in the hands of a few Hebrew families. For modern observers, however, the greatest danger by far would have resulted from the pollution of the genetic pool because of inbreeding. The bulk of the relationships prohibited by the legislation involved first and second degrees of consanguinity, that is, parent-child and grandparent-grandchild incest. Coition within the forbidden degrees of family relationships generally results in genetic complications when offspring are produced. Recessive genes often become dominant and endow the fetus with various kinds of diseases or congenital malformations. This seems to have been the force of the Hebrew tebel [l, b, T], a word that occurs only in Leviticus 18:23 and 20:12. It comes from balal [l; l' B], meaning “to confuse,” and conveys aptly the genetic upheaval that occurs in many cases of inbreeding, since God's rules for procreation have been upset. Only in a few instances does close inbreeding produce beneficial effects by removing recessive lethal genes from the genetic pool. (This may have happened in the case of ancient Egyptian royalty.) Nevertheless, even in such instances, inbreeding diminishes the energy and vigor of species that are normally outbred, and reinforces the wisdom and authority of the Mosaic legislation.

When God entered into a covenant relationship with the Israelites he furnished them with certain fundamental regulations engraved in stone to symbolize their permanence. These “Ten Commandments,” as they are styled, contain certain injunctions of a moral character dealing with adultery, theft, false witness, and covetous behavior (Exod. 20:14-19).The last three offenses are social in character, involving the community of God to a greater or lesser degree. But the commandment prohibiting adultery deals with an act of a highly personal nature, occurring between normally consenting adults, which violates the “one flesh” character of marriage.

The fact that a commandment deals specifically with this form of behavior seems to indicate that adultery was common among the ancient Hebrews. At all events, adultery was understood as sexual intercourse between a man and another man's wife or betrothed woman. Similarly, any act of coition between a married woman and a man who was not her husband was also regarded as adultery. Certain exceptions to these stringent rules were tolerated in Old Testament times, however. A man was not considered an adulterer if he engaged in sexual relations with a female slave (Gen 16:1-4), a prostitute (Gen 38:15-18), or his wife's handmaid with the spouse's permission (Gen 16:4). Nor was a man deemed to be in an adulterous relationship if he happened to be married to two wives.

The traditions banning adultery, made specific in the Decalog, were enshrined deeply in Israel's national life. The prophets warn that divine judgment will descend upon those who practice it (Jer. 23:11-14; Ezek. 22:11; Mal 3:5). The Book of Proverbs, however, takes more of a social than a specifically moral view of adultery, ridiculing it as a stupid pattern of behavior that leads a man to self-destruction (6:25-35). The prophets use the term figuratively to describe the covenant people's lack of fidelity to the high ideals of Mount Sinai. The prophets view the covenant as equivalent to a marriage relationship between God and Israel (Isa 54:5-8). Any breach of the covenant, therefore, is an act of spiritual adultery (Jer. 5:7-8; Ezek. 23:37).

In his teachings Jesus stands firmly in the traditions of the Mosaic law and prophecy by regarding adultery as sin. But he extends the definition to include any man who lust sin his mind after another woman, whether she is married or not. It is thus unnecessary for any physical contact to take place, since the intent is already present (Matt 5:28). By this teaching Jesus demonstrates that, under the new covenant, motivation is to be considered just as seriously as the mechanical act of breaking or keeping a particular law. The motivation of a believer should always be of the purest kind, enabling obedience to God's will freely from the heart, and not just because the law makes certain demands.

Whereas the female is cast in an inferior, passive role in the Old Testament sexual legislation, Jesus considers the woman as equal to the man in his teachings about divorce and remarriage. In consequence the woman has to bear equal responsibility for adultery. Much discussion has taken place about Christ's return to the strict marriage ideals of Genesis 2:24 (Mark 10:6) and the explanatory clause “except for marital unfaithfulness” (Matt 5:32; 19:9), which allows for remarriage after divorce and which does not occur in either Mark 10:11 or Luke 16:18.

Before New Testament technical terms are discussed, it is important to realize that Christ was directing his teaching at the new age of grace, which in his death was to render Old Testament legal traditions ineffective. The Mosaic Law was specific about the conditions under which divorce could occur. The wife had fallen into disfavor because her husband had found something unclean or indecent about her, and therefore he was entitled to divorce her. Jesus teaches that this procedure was allowed by God as a concession to human obduracy (Matt 19:8), even though the Creator hated divorce.

In New Testament times, only the man was able to institute divorce proceedings. It was in reality, however, a rare occurrence, and at that mostly the prerogative of the rich, since poor men could not afford another dowry or “bride price” for a subsequent marriage. The accused woman was protected under the law to the extent that her husband's accusations had to be proved. Thus some scholars have seen the Matthean explanatory clause as indicating immorality as the sole ground for divorce, following the contemporary rabbinical school of Shammai, and not for some purely frivolous cause, as the school of Hillel taught. If this explanation is correct, Jesus was addressing a Jewish controversy that had no bearing on God's marriage ideals in the age of grace, and which Mark and Luke consequently ignored because the exception did not apply to their audiences of Christian believers.

The most common term in the New Testament for sexual immorality is porneia [porneiva], and its related forms pornos [povrno] and porneuo [porneuvw]. An emphatic form of the verb, ekporneuo [ejkporneuvw], “indulging in sexual immorality, occurs in Jude 7. These words have been translated variously into English, some renderings for an immoral person being “who remonger,” “fornicator,” “loose liver,” and “sexually immoral.” The term pornos [povrno] refers to a man who engages in coition with a porne [povrnh], or female prostitute. The extended description of wanton immorality in Romans 1:24-32 discusses women spurning natural sexual relationships for unnatural ones, that is, indulging in lesbian activities of the kind practiced at Lesbos in pagan Greek religious ceremonies. The males are described as inflamed with lust for one another, and this leads to indecent and immoral behavior. In 1Corinthians, 6:9 the sexually immoral are classified as adulterers, male prostitutes, and homosexual offenders. In 1Timothy 1:10, sexually immoral people are described comprehensively as adulterers and perverts.

The New Testament contains far less teaching about sexual immorality than the Old Testament, on which Christian morals and ethics are based. The Mosaic Law condemned adultery, but placed less emphasis on prohibiting some other sexual offenses. In the end, disregard for the Mosaic enactments brought Israel to ruin and this made it important for the Christian church to distinguish carefully, among other matters, between adultery as a sin and porneia [porneiva], which was a fatal perversion.

The New Testament requires believers to deny physical and spiritual lusting after people and false gods, and to conduct their behavior at a high moral and spiritual level. Sexual activity is to be confined to the marriage relationship, and if a married man or woman has sexual intercourse with someone other than the spouse, that person has committed adultery. To be most satisfying for the Christian, sexual activity must reflect the values of self-sacrificing love and the unity of personality to which the Christian's reconciliation to God by the atoning work of Jesus brings the believing couple. R. K. Harrison (2)

In closing:

There is no excuse for someone to plead ignorance of the biblical teaching on sex outside of marriage, i.e. fornication.

“To God, only wise, be glory through Jesus Christ forever. Amen.” (Romans 16:27) and “heirs according to the promise.” (Galatians 3:28, 29)


1.      W. E. Vine, An Expository Dictionary of New Testament Words, (Iowa Falls, Iowa, Riverside Book and Bible House), p. 455.

2.      Walter A. Elwell, Editor, Baker’s Evangelical Dictionary of Biblical Theology, (Grand Rapids, Michigan, Baker Book House), p. 367-371.

Mr. Kettler has previously published articles in the Chalcedon Report and Contra Mundum. He and his wife Marea attend the Westminster, CO, RPCNA Church. Mr. Kettler is the author of the book defending the Reformed Faith against attacks, titled: The Religion That Started in a Hat. Available at: http://www.TheReligionThatStartedInAHat.com

For more study:

Counting the Cost of Sexual Immorality by Randy Alcorn https://www.epm.org/blog/2009/Jun/26/counting-the-cost-of-sexual-immorality

Paul Washer | 1 Thessalonians 4:1-3 | Abstain from Sexual Immorality | https://www.youtube.com/watch?v=YQPRp2K8LjA