Fornication in the Bible: Meaning & Verses

Disclaimer: The views and opinions expressed in this article belong to the author and do not necessarily match my own. - Dr. Bart D. Ehrman

The word “fornication” appears frequently in English translations of the Bible, yet its meaning is far less straightforward than it might seem at first glance. While modern readers often assume it refers simply to sex between unmarried people, this definition reflects a relatively narrow and later understanding of the term. In the biblical texts themselves, the words translated as “fornication” carry a much broader and more complex range of meanings shaped by ancient cultural, social, and religious contexts.

In this article, I’ll explain how these terms function across both the Old and New Testaments, tracing how their meanings shift depending on context. By looking closely at the linguistic roots and the historical settings in which these words were used, we can better understand not only what biblical authors may have intended, but also why translating and interpreting “fornication” in the Bible remains such a challenging and often debated task today.

Translations and Definitions of Fornication in the Bible

In most English dictionaries, fornication is defined simply as sexual intercourse between people not married to each other. However, as we’ll soon see, the Hebrew and Greek words frequently translated as fornication often contain much broader connotations.

Let’s begin with Hebrew. The Hebrew verb usually translated as “to commit fornication, prostitution, or unfaithfulness” is zanah, while the related noun zonah generally means a prostitute or harlot. Forms of these words are found many times in the Hebrew Bible, although not always in the same contexts. In my discussion of the use of these words in Old Testament books, I’ll go into more detail about the ways various forms of this word are used.

Meanwhile, the Greek word often translated as fornication in the New Testament is porneia, from which we derive English words like pornography. However, translating this word is a tricky business and requires some background.

In his book The Corinthian Body, Dale Martin notes that "the precise meaning of porneia is simply uncertain given the lack of evidence we have." It’s not that we don’t know the general gist of the word: porneia always refers in some sense to sexual immorality. The problem is that different cultures and times in history have defined sexual immorality differently. As Carolyn Osiek has noted in Early Christian Families in Context, "To say that πορνεία [porneia] means fornication is circular, and the concept of illicit sex only begs the question of what is considered illicit." For an example of this, let’s discuss the difference between adultery (Greek: moicheia) and fornication (porneia) in the ancient Greek-speaking world.

In his article, “Porneia: The Making of a Christian Sexual Norm,” Kyle Harper notes that the line dividing these two concepts was entirely determined by the status of the woman involved.

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For modern people, adultery and fornication can overlap. If a person is married and has sex with someone to whom he is not married, he is an adulterer. But since the two having sex are also not married to each other, they are also committing fornication according to the dictionary definition above.

Harper notes that the word porneia, “derived from the Greek pornē ("prostitute")… passed into Latin as fornicatio and thence into English as "fornication." But "fornication" is effectively limited to ecclesiastical usage.”

He goes on to remark that while the definition of the English word fornication has narrowed over time, the definition of porneia gradually broadened in Greek. Since it was originally derived from the word pórnē as noted above, Harper writes that porneia first meant simply "the practice of selling access to one's body. Porneia in classical Greek, refers [only] to the activity of the seller.” However, he reports that this meaning would eventually expand:

These sexual standards were only applicable when “free women,” those who were not slaves, had a respectable marriage, and were not prostitutes, were involved. However, Harper notes that long before the advent of Christianity, “Athenian law held that a man was not a μοιχός [adulterer] if he had sex with a woman who sits in a brothel or sells herself openly… The μοιχός violates a [free] woman, not his own marriage bond; there is no female equivalent.”

In other words, the classification of sexual violations had more to do with the status of the woman involved than with any objective moral standard. Men with respectable marriages could have sex with slaves or prostitutes without technically violating their marriages. On the other hand women, even free women, were not given the same liberty.

Having established some of the nuances of the translation issues involved in this topic, let’s move on to how the Bible uses the word fornicate (or its equivalents) in the Old Testament.

Fornication in the Old Testament

We begin with the earliest iteration of zanah, the Hebrew word often translated as fornication in the Hebrew Bible canon. It’s found in the story of Tamar and Judah in Genesis 38. Tamar is widowed twice after the deaths of Judah’s sons Er and Onan. However, Judah fails to fulfill his obligation to provide his third son, Shelah, as her husband, leaving Tamar in a vulnerable and dishonorable position. Realizing she has been wronged, Tamar disguises herself as a prostitute and sleeps with Judah, who does not recognize her. When she becomes pregnant and is accused of prostitution, she reveals items Judah gave her as payment, proving he is the father. Judah admits his wrongdoing and declares Tamar more righteous than himself.

The word zanah in this story comes in verse 24 when it is discovered that Tamar is pregnant:

Notice that zanah here refers only to prostitution or paid sexual favors. However, in another book in the Pentateuch, we soon see the metaphorical use of the word, a use which becomes far more common than the literal use of the term in the Old Testament.

In Numbers 14:33, we see this sentence using a form of zanah in a figurative way:

The context of this passage is the 40 years the Israelites have wandered in the wilderness looking for the Promised Land. In this sentence, the Hebrew word zanūṯêḵem, which can mean extramarital sex, is used for unfaithfulness to God, otherwise known as idolatry. In fact, this word is used frequently to mean worship of idols in further passages.

Another example of this use can be found in 2 Kings 9, which describes an Israelite warrior named Jehu overthrowing the wicked king Ahab and killing his wife Jezebel. However, before Jezebel is killed, we see this short dialogue in verse 22:

Although calling a woman a “Jezebel’ once meant an accusation of sexual promiscuity in English, this is not what Jehu accuses Jezebel of. Instead, he charges her with serving idols rather than the God of Israel. In other words, her “prostitutions” are simply unfaithfulness to God.

A final example comes from the prophets who use this metaphor of fornication-as-idolatry more than any other Old Testament books. In Jeremiah 2:20, God speaks through the prophet, telling the Israelites

In this entire chapter, God begs his people to repent for worshipping other gods, specifically the Canaanite gods of the people around them. This is depicted as a form of “prostituting” themselves, selling their allegiance to other gods to get what they want or establish bonds with other peoples rather than serving their own God. As Harper notes,

But what about the New Testament? Is there any continuity with the Hebrew Bible’s figurative reading of fornication or prostitution as idolatry?

Fornication in the New Testament

In most Greek lexicons, the word porneia is defined as sexual immorality, fornication, marital unfaithfulness, prostitution, adultery, or simply as a generic term for sexual sin of any kind. In other words, it can be used to mean something very specific or something general and vague, making it a hard word to translate accurately. To do so, we need to look at specific verses in the New Testament and analyze their use of the word according to the specific contexts.

Let’s start with the Gospels. In telling the Pharisees what defiles a person in Matthew 15:19, Jesus refers to porneia as one item in a long list of sins:

The King James Version (and several other versions) translates porneia as “fornication.” But since Jesus doesn’t specify, and since the word in Jesus’ time could mean so many different types of sexual immorality, it’s difficult to know his intention. We find the same problem in Mark 7:21, of which Matthew is essentially a copy. Does it indicate prostitution? Sex with someone outside marriage? Pederasty? All of the above? It’s impossible to know for sure.

In fact, the same broad term is used in Acts 15:19–20, in a letter sent from the Jerusalem Church to Gentile converts:

While it may be significant, given the metaphorical use of fornication/prostitution as idol worship in the OT, that the letter specifies both idol worship and sexual immorality as prohibited, their equivalence is not stated explicitly.

However, the author of Acts—who also wrote the book of Luke—seems to assume that his readers will know what porneias means, and therefore avoids mentioning specific sexual prohibitions. However, one thing is clear from this passage: as Jennifer Wright Knust writes in her book Abandoned to Lust: Sexual Slander and Ancient Christianity, the word porneia is used rhetorically to define a moral failing associated with depraved outsiders. In this and many other cases in the NT, Christians are defined as those who do not engage in porneia.

Paul epitomizes this exclusionary meaning of the word in 1 Corinthians 5:1–5:

Questions about this passage remain. For instance, is the man who is living with his father’s wife committing porneia simply in the sense that they aren’t married to each other? Or because it is legally defined as incest? Or because it is adultery? Note that all of these seem to be the case, indicating that for Paul, writing in the 1st century CE, porneia can be broadly applied to all of them.

In addition, the fact that Paul wants this man thrown out of the group makes Knust’s point that the word was primarily used in writing for the purpose of defining who was in (members of the church who are not committing porneia) and who was out (those who commit some form of porneia).

Finally, we find several verses in the NT which clearly harken back to the OT use of the word zanah to indicate the sin of idolatry. These occur principally in the book of Revelation, which uses many OT themes to communicate its message about the eschaton or end of the world. In Revelation 2:21, for instance, in a letter to the church at Thyatira, John of Patmos writes this:

Note that first of all, John calls this female false prophet Jezebel, a name he almost certainly gives her for rhetorical purposes. Second, sexual immorality here is intertwined with idol worship, just as it is figuratively in the Hebrew Bible. We see a similar conflation in Revelation 14:8:

In the book of Revelation, Babylon is the code word for Rome. Calling Rome a prostitute is the same as calling her an idol-worshipper, especially since Rome was polytheistic and persecuted Christians for refusing to worship Roman gods. Revelation 17:5 makes this even more explicit. John sees a woman clothed in the royal color of purple and wearing extravagant jewelry, representing the Roman emperors,

This is not a characterization of Rome as sexually immoral, but rather as idolatrous. Rome is again compared to Babylon, the earlier empire which also destroyed Jerusalem and the Temple and forced Jews to worship idols. By this last book of the Bible, we have, in a sense, come full circle: porneia is explicitly associated with idolatry, just as it was in so many places in the OT.

Conclusion

Translation is always a tricky business, especially with texts as old as those in the Bible. Languages, even those like Greek and Hebrew which have survived, change drastically over time. This is why so many different English translations of the Bible have been made: there remain many different opinions on how best to translate important words like “fornication.”

The Hebrew word zanah is one of these. Literally meaning prostitution, promiscuity, or unfaithfulness, we find that, while some early OT texts use this literal meaning, many of the later books use this word figuratively to signify idol worship as infidelity to God.

With the Greek word porneias, the problem of translation is intensified. This word was used in the social and linguistic world of the NT to mean just about every kind of sexual immorality one can imagine: sex between unmarried people, sex between those not married to each other but married to other people, prostitution, incest; the list goes on and on. While we can surmise that readers and hearers of those texts in their time must have understood what the authors meant, 2,000 years later we can only speculate.