What does "two becoming one flesh" refer to?

One flesh - Connected sexually first. The result is "one flesh", a newborn baby that is "one flesh" of the woman and man who joined together.

Also it means the two of you are now one "until death do (you) part". One team raising a family. One set of loving parents guiding their children. One set of legs, arms, eyes, mind working to fulfill the will of God.

In the old testament the Tabernacle and later, the Temple, was the dwelling place of the essence of God on earth. It was the center of Spiritual life. After Pentecost, our human bodies became The Temple where the Spirit "in dwells."

During the act of procreation, the male and female bodies are indeed conjoined as one, but this temporary union always ends with the death of the sperm and egg; unless a new beautiful human life is created. God's purposes are to bring life, not death. The new birth, is a lovely, unique human being created by the "union" of the mother & father's individual DNA. "Therefore the two become one." This beautiful and unique union cannot be denied by any one. Not the father, mother or the child, no matter how much they may wish is to be so. It cannot be undone nor torn apart.

But in God's Kingdom, this new birth means much more than a new "human being." Jesus was begotten, not made. He exists through all time. But when a child is born, don't we believe a new "eternal being" is created at that moment? This is a life giving, eternal an act of co-creation with God, not a crude, temporary act of procreation between two worldly creatures. For the child is a new eternal being! And not only eternal, but an eternal being created in the image of God. And not just in God's image, but ultimately, becomes temple for The Holy Spirit. A sanctuary for God's presence on earth. The new place from which Spiritual life on this planet emanates. The Holy Spirit is to become that child's Advocate, Counselor, Comforter and Intercessor for the glory of God on earth and in the heavens...

You all need to stop looking through your human eyes, applying your human logic, trying to use your human understanding of what 'one flesh' really means. Instead, look at 'one flesh' from the Creator's perspective, from God's perspective. What do you think God sees at the union of a man & a woman in marriage? From that moment forward, at the creating of the covenant of marriage between a man & a woman, God then sees them as 'one flesh'. Whenever He sees the Husband He also sees the Wife & vice versa. One flesh has nothing to with sexual intercourse between a husband and a wife. No matter how many times they may be intimate they always remain two flesh. Consider the war veteran who returns home with his genitals blown away by a landmine, he marries but is unable to have sexual intercourse with his wife. Is he and is wife excluded from being 'one flesh' because they can't have intercourse? Of course not, God sees them as 'one flesh' from the moment they enter into their marriage covenant with Him. Is the husband and wife who are not able to have children excluded from being 'one flesh'? Of course not, God sees them as 'one flesh' from the moment they enter into their marriage covenant with Him.

When man and woman have sex they enter a state called "one flesh" regardless of whether they are virgin or married or in fact having sex with a prostitute. You can be "one flesh" with many but God intends only one (living). "One flesh" is a state of spiritual union initiated by a fleshy act which can only be ended by death. The act of marriage creates a physical union and this should correspond with the spiritual union , so sex and marriage go together, even if the sex comes first. Jesus made a definitive statement on sex and marriage in Matthew 19.4 onwards which has deep spiritual meaning as well as a very simple literal meaning ; we wouldn't expect less from the top spirit himself. Over the years the Church has emphasised the marriage union and shied away from the "one flesh union" because it can easily control the former. The bible is a spiritual guide and the words used don't always do justice to the message. To those of you who have received messages from the Holy Spirit you will recall that you receive the message not in words; but your brain assigns words to it in a clumsy way...so when we read the Bible we ask the Holy Spirit to give us the understanding.

I believe, as was stated by Chris, that "one flesh" is essentially created by the act of physical union in the act of sexual intercourse and I do believe that this is by God's design. Sexual activity was never meant to be taken lightly and was never meant to be something between many partners but between one man and one woman.

I say this because of what it says about sexual activity in the bible it also from personal experience. I believe firmly that a spiritual bonding takes place during the physical act that is not easy to dissolve. Having multiple partners outside of marriage creates multiple spiritual bonds and interferes with any future permanent relationship. I also personally believe that these bonds need to be recognized, confessed and renounced before God if they are not to cause a problem within the marriage relationship.

I am brand new to this forum. I found this page while searching this topic on Google. But, I joined and read the rules and the information about how the site works, and I'm not sure how the answer that Mark Russell has allowed to even stay on the site for 4 years!! While we are all entitled to our opinion, this is not the place for unsupported opinions. This is a place to share biblical or denominational based information. I see neither in this answer. It appears to be only opinion due to the lack of sources cited. (I'm not saying that it is only opinion, but without your citing of information supporting your opinion, your "answer" does not offer much to Albert Renshaw (the author of the question). The statement that I bothers me most in your "answer" (and I would like to know what doctorine or source was used to determine this) is this, "One flesh has nothing to do with sexual intercourse between a husband and wife. No matter how many times they may be intimate they always remain two flesh." How can you support this statement? More specifically, where in the Bible does it say that when a man and woman marry, they become one flesh, ONLY IN THE EYES OF GOD. THEY ARE STILL TWO FLESH IN THE EYES OF ALL OTHERS? And I'm asking this seriously. Because I looked it up and can't find anything that supports this statement biblically, but if I'm wrong and just haven't found the passage, I can accept that. If you didn't come to this conclusion from the Bible, please edit your answer to let us know where your theory is deriven from. I agree, that "becoming one flesh" isn't only referring to the sexual act in every verse that the phrase is found within the Bible (I find 8 verses that use the phrase "becoming one flesh"). Although when Paul wrote his first letter to the Church of Corinth he addressed sexual immorality in chapter 6. Verses 15 and 16 say, "(15) do you not know that your bodies are members of Christ? Shall I then take the members of Christ and make them members of a prostitute? Never! (16) or do you not know that he who is joined to a prostitute becomes one body with her? For it is written, The two will become one flesh (Paul quotes Gen 2:24)." (ESV). Paul is absolutely referring to the sexual act resulting in two becoming one flesh and is defining the becoming of one flesh through sexual intercourse. Leading us to assume that we can also define it this way in marriage, especially since he refers directly back to Genesis 2:24: "Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh."

The exact phrase: "Two becoming one flesh " is referenced in the bible 5 times (correct me if I'm missing some). Genesis 2:24, Matthew 19:5-6, Mark 10:7-9, 1 Corinthians 6:16, Ephesians 5:22-33. In all of these 5 passages; it references a husband and wife (2) becoming one flesh. There are sexual implications in all 5 passages. In Ephesians Paul speaks to Christ nourishes and cherishes the church like a husband should love his wife. But what I don't see in this passage is the phrase, "Christ and the Church will become one flesh." Instead Paul says this: verse: 29)"For no one ever hated his own flesh, but nourishes and cherishes it, just as Christ does the church, 30) because we are members of His body. 31) Therefore a man shall leave his mother and father and hold fast to his wife, and the two shall become one flesh (quoting Gen 2:24 again). 32) This mystery is profound, and I am saying that it refers to Christ and the church. 33) However, let each one of you love his wife as himself, and let the wife see that she respects her husband.

So back to the original question does the phrase found in multiple passages in the bible "two becoming one flesh" refer JUST to sex: no. But does it refer to sex in at least one passage? Absolutely and I feel like I have proven that with contextual evidence (1 Corinthians). Does it refer to offspring: while I don't have the time now to answer that question definitively, with proof, my opinion is that it can mean that.

Here's the thing. Anytime you are interpreting scripture or searching for the meaning of a phrase that is found in multiple passages throughout the Bible, you must research and study each passage separately. When you assume that the phrase has the same meaning, implications, and applications in every place it's found, you miss the whole reason that it was written more than once. That's where exegesis and hermeneutics is vital. By just focusing on the one phrase "two become one flesh," you miss the big picture. In order to understand what it means in 1 Corinthians, you must first study the context in which it is found. The entire passage is crucial to the meaning of the phrase. It's important to know who the "book" or in this case "letter" was written to. Who was Paul addressing--the church of Corinth. What was going on within the church at that time? Was it written before Jesus came or while he was in his ministry or after his victorious resurrection. After you do an in depth study including taking a look at the passage in the original language and looking at how it was translated word by word--you will have a better understanding of what that phrase meant and why it was important for Paul to repeat it to those people at that time, then you can make a better application of what that means to us today. Then go back to Genesis. The phrase is found there before the fall. When Eden was filled with nothing but perfection. Exactly how God had intended before sin entered the world. In Matthew, Jesus uses the phrase. He used it in response to a question that the Pharises were using to test him. In that passage, the focus is divorce and they were trying to trip him up. In his response to their question--he went back to Eden. Before the fall. They asked him if divorce was lawful and he basically said, "did you not read the creation story?!? That he created man and woman "a man shall leave his father and mother and hold fast to his wife, and the two shall become one flesh? So they are no longer but one flesh. What therefore God has joined together, let not man separate." (Matt 19:6). The Pharisees came back with---well, didn't Moses grant a divorce--why?!? (Paraphrased verse 7) and Jesus replied, "because of your hardness of heart Moses allowed you to divorce your wives, but FROM THE BEGINNING IT WAS NOT SO. And I say to you: whoever divorces his wife, except for sexual immorality, and marries another, commits adultery." (Verse 8-10). Jesus was saying, "divorce wasn't in the plan. That's not how it was in the beginning. But because sin entered the world and you are all sinners, the plan got messed up. But, I'm telling you that you are committing adultry when you divorce your wife and marry another. Adultery is a sexual sin, so we can draw a pretty good conclusion that when he refered back to the two becoming one, it had the implication of a sexual act as well as a implication of the commitment that is broken with divorce; which is why if you marry another you are committing adultry unless your spouse was committing sexual sins against you and God as well.

So if you truly want to know the meaning of the phrase. Pick a place that you find the phrase in the Bible and study as much as you possibly can about the entire passage. Even if it's word for word the same in our English Standard Versions, take a look at the original text for a more in depth understanding. The translators have done a great job matching up the Greek and Hebrew words with words that mean almost the exact same thing to us in today's English language. And scholars evaluate and re-translate often as language constantly evolves. So something that meant one thing back in an older translation (i.e. Old King James) doesn't always have the same connotation in today's society--which is why you see a constant offering of new translations. When I'm doing an in depth study of a passage I usually focus on one section of a chapter at a time. and I read the same passage in as many translations as I can and always look at the Greek or Hebrew bible too. Look up every single word of a passage and compare the Greek to your other translations. You will be amazed at how the Bible will reveal itself to you. I am always amazed at how it is truly the living breathing word of God that is as applicable to me as it was to that church in Corinth the day they read their first letter from Paul. But understanding them, helps me understand the words found in that book on a much deeper level. :-).

One flesh is caused by sexual intercourse, and nothing more. But one flesh itself is the state of being metaphorically and spiritually one body with another. The wife's body does not belong to her, but to her husband, and vice versa, because they are one flesh and their bodies are the same. (1 Cor 7). Similarly, we are one in spirit with Christ, and our bodies do not belong to us, but to Him, as His body belongs to us, as He gave it to us on the cross. (1 Cor 6:17) Paul says this is a mystery, but in the Greek, mystery does not mean "something that is unknowable." HELPS Dictionary says this about mysterion:

the Bible, a "mystery" (3466 /mystḗrion) is not something unknowable. Rather, it is what can only be known through revelation, i.e. because God reveals it.[some][3]

Consequently, ALL mysteries are only mysteries after they have been revealed, for we don't know about them until they are revealed to us!

"Marriage is a mystery." Christ, in His divinity, revealed that His relationship to us is analogous to a marriage, and that is the full extent of the "mystery" of marriage.One flesh ties into all of that because we are one spirit with Christ. We enter into a one spirit relationship with a singular act of faith, and similarly, for our bodily unions we enter into a one flesh relationship with a singular act of physical union. That is, sex.

1 Cor 6:16 Or do you not know that anyone who is united with a prostitute is one body with her? For it is said, “ The two will become one flesh .”

The grammar Paul uses here suggests that he is equating one body to one flesh, as the transitional word gar is used, which denotes causation. This gives us the assurance that sex causes two people to become one flesh.

Matt 19:3-6 Then some Pharisees came to him in order to test him. They asked, “Is it lawful to divorce a wife for any cause?” He answered, “Have you not read that from the beginning the Creator made them male and female , and said, ‘ For this reason a man will leave his father and mother and will be united with his wife, and the two will become one flesh ’? So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”

Jesus says that it is God who puts together two people into one flesh. According to Paul, this means that God puts together those who are one flesh whenever they have sex. And then Jesus states that what God has put together, let no man separate.

The ramifications of this are not hard to see. If sex makes you one flesh, and those who are one flesh are not to separate, then that means they must cleave to each other. Sounds a bit like a marriage, does it not? And considering that Jesus was speaking on divorce, it seems likely that He was insinuating that you become married, and thus able to divorce and commit adultery in God's eyes upon having sex. This certainly would explain the plethora of verses on adultery and adulterous people in the Old Testament and the great lack of passages of premarital sex.

The story that speaks the most evidence into this definition of one flesh equating to sex equating to marriage is the story of Jacob, Rachel, and Leah in Gen. 29.

Jacob and Rachel were betrothed, which in Hebrew culture meant they were husband and wife by covenant (v. 21), but they did not have sex. According to Hebrew custom, Jacob paid a dowry to Laban, the father, for Rachel (v. 18). Then they held a wedding feast for Jacob and Rachel with many people there, presumably also within Hebrew customs (v. 22). According to our standards today, Jacob and Rachel were at this point more than married enough to be considered united and separated from Laban. They were married under a covenant, and they had a wedding. Yet when Jacob has sex with Leah, we see that he has to pay another 7 year dowry for Rachel, again! Apparently those dowries went to whoever you ended up having sex with, not the person you made a covenant with. The covenant meant basically nothing in terms of the right to "own" Rachel, it would seem.

From the other angle, let us consider Leah's marriage to Jacob. Leah and Jacob were not betrothed, or Jacob would not have been angry upon having sex with her (v. 25). The wedding was not for Jacob and Leah, or Jacob would have known about the deception. Yet when Leah and Jacob have sex, apparently the dowry transfers to her, and Jacob apparently has to agree to keep her as his wife in order to obtain Rachel. Sounds an awful lot like sex made them married, despite the lack of covenant.

Now let's look at the story from Laban's perspective. Laban knew all along that he was going to deceive Jacob into having sex with Leah. But here's the thing: what purpose would deception serve if sex has no inherent commitment? Laban would essentially just lower Leah's virgin status needlessly, as the sex would constitute just premarital sex, and he would have angered his potential son-in-law needlessly, and in this day, such a thing was potentially mortal in danger.

No, the only way Laban's plan of deceit makes sense is if he has the capability of "tricking" Jacob into marrying Leah, which points directly to the idea that sex is marriage. Conversely, the only thing lacking in Jacob and Rachel's marriage was sex, and without that, Jacob could not have left Laban's household without her.

Now there are laws in Exodus 22:16-17 and Deuteronomy 22:28-29 that show us that Hebrew law dictated exactly these consequences for this situation, but we cannot simply say that sex is marriage here because the law said so. No, we must say the law said so because sex is marriage, because this story happens hundreds of years before those laws were ever given!

The ramifications are far reaching, and there is far more discussion to be had about the idea that sex is one flesh is marriage, as well as many more proofs, but I will leave it at this.

To more specifically answer your question, one flesh is begun at the point of sexual intercourse, but it is not intercourse itself. One could say that it is, along with being metaphorically the same body, the state of perpetual possibility of conception. Even with barren people, the possibility of conception is there because God is in control of conception, as we see with Abraham and Sarah. If you are opening the door to conception to God, then you are one flesh.

The saying the Bible "The two become one flesh" is almost always in reference to marriage and all that it means.

The saying is found in Genesis 2:24, when God instituted marriage, Mark 10:8, when Jesus was commenting on the permanent nature of marriage, and Ephesians 5:31, when Paul uses marriage as a symbol of the relationship between Christ and the church.

The full extent of the verses in Genesis is:

23 The man said,
“This is now bone of my bones
and flesh of my flesh;
she shall be called ‘woman,’
for she was taken out of man.”
24 That is why a man leaves his father and mother and is united to his wife, and they become one flesh.

In Ephesians, when Paul quotes Genesis he says "This mystery is profound," then moves back on topic about Christ and the church. This really only tells us that it is likely we cannot really understand the connection between a man and a woman in marriage.

The only truly reveling verse is Mark 10:8. Jesus is directly questioned if divorce is acceptable. He responds by quoting Genesis then says "Therefore what God has joined together, let no one separate." This is simply that marriage is permanent. You cannot leave your marriage because God joined the two together.

There is a similar question here that should shed more light on the topic.

Summary in short: "Two become one flesh" is about marriage and the mysteries within that institution.

In Hebrew, Genesis 2:24 reads:

עַל־כֵּן֙ יַֽעֲזָב־אִ֔ישׁ אֶת־אָבִ֖יו וְאֶת־אִמֹּ֑ו וְדָבַ֣ק בְּאִשְׁתֹּ֔ו וְהָי֖וּ לְבָשָׂ֥ר אֶחָֽד

The fully understand what the verse means, it is helpful to look at a few key words more closely.

וְדָבַ֣ק

Comparing several translations, there is a wide variety on how the verb וְדָבַ֣ק is translated. The NIV uses "is united", ESV "hold fast", NASB "be joined", NRSV "clings", while older translations (KJV, ASV, Douay-Rheims) use "shall cleave". Cleave is an archaic word that is not really used much anymore, but its seems every modern translation uses something different, so let's look at the original Hebrew.

The root of וְדָבַ֣ק is דָּבַק (dabaq). The verb occurs 54 times in the Old Testament. It can have a literal meaning of cling/stick to, for example Job 19:20:

My bones stick (דָּבְקָ֣ה) to my skin and to my flesh, and I have escaped by the skin of my teeth. (ESV)

It can also be used figuratively, as is presumably the case on Genesis 2:24. BDB suggests passages that likely use dabaq is the same sense as our passage:

And his soul was drawn (וַתִּדְבַּ֣ק) to Dinah the daughter of Jacob. He loved the young woman and spoke tenderly to her. (Genesis 34:3, ESV)

from the nations concerning which the LORD had said to the people of Israel, “You shall not enter into marriage with them, neither shall they with you, for surely they will turn away your heart after their gods.” Solomon clung (דָּבַ֥ק) to these in love. (1 Kings 11:2)

For if you turn back and cling (וּדְבַקְתֶּם֙) to the remnant of these nations remaining among you and make marriages with them, so that you associate with them and they with you, (Joshua 23:12)

Then they lifted up their voices and wept again. And Orpah kissed her mother-in-law, but Ruth clung (דָּ֥בְקָה) to her. (Ruth 1:14)

and so on. The common theme here seems to a deep emotional attachment. Two of the passages specifically mention marriage, and the Genesis 34 passage eventually leads to marriage as well.

That said, dabaq can also be used for "overcome" and "keep", but what one does not find in any of the 54 Biblical uses is a sexual connotation.

To back up BDB's classification of Genesis 2:24 as emotional attachment instance, we can see how ancient translators, who were much closer to the original language than we are, took the word. The Septuagint has προσκολληθήσεται, which has a literal sense of "stick to", but when used in regards to human relationships means something like "be faithfully devoted to", especially when used to describe husband-wife relations. (BDAG)

Targums Onkelos and Neofiti have וְיִדבֹק which has more or less the same range of usage as dabaq. Pseudo Johnathan, however, uses מִבַעֲלַה which can mean "be associated with" or "make a partner of".

Finally, the Peshitta has ܘܢܩܼܦ which can mean "adhere to", "join to", or even "be betrothed to".

As such, the ancient translations support understanding וְדָבַ֣ק as joining together in a close relationship. The NET translation notes agree with my analysis, writing:

The perfect with vav (ו) consecutive carries the same habitual or characteristic nuance as the preceding imperfect. The verb is traditionally translated “cleaves [to]”; it has the basic idea of “stick with/to” (e.g., it is used of Ruth resolutely staying with her mother-in-law in Ruth 1:14). In this passage it describes the inseparable relationship between the man and the woman in marriage as God intended it.

(They explicitly connect the passage to marriage, which I have not yet done, but I felt the quote fit best here rather than later.)

לְבָשָׂ֥ר

Genesis 2:24 states that the man and women shall be/become one flesh (לְבָשָׂ֥ר). The root word בָּשָׂר (basar) is used quite often in the Old Testament (270 times). It is usually translated as flesh, but occasionally body.

The key to understanding the word here is to notice that it is also used in Genesis 2:21 and 2:23:

So the LORD God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh (בָּשָׂ֖ר). And the rib that the LORD God had taken from the man he made into a woman and brought her to the man. Then the man said, “This at last is bone of my bones and flesh (וּבָשָׂ֖ר) of my flesh (מִבְּשָׂרִ֑י); she shall be called Woman, because she was taken out of Man.” (Gen 2:21-23, ESV)

The author of Genesis is making an analogy. The flesh (literally a rib) that was taken from Adam to create Eve is metaphorically "returned" to create a whole. Adam is missing apart of himself. He is literally and metaphorically incomplete without Eve. Likewise, a man is incomplete without a woman. The author is saying that man needs to be united with woman.

עַל־ כֵּן֙

This connection, while obvious enough from the repeated use of basar, is made explicit in the text. The Hebrew phrase עַל־ כֵּן֙, translated by the KJV as "therefore", draws a connection between what precedes and what follows. The previous verse(s) provide the reason why a man leaves his parents, seeks out a woman, and unites with her to become one flesh. Furthermore, it sets up Genesis 2:24 as a comment on the preceding verse by the narrator; that is, distinguishes it from Adam's speech. (Compare Genesis 10:9; 26:33; 32:32.) As such, the NET translates the phrase "That is why".

Nature of the union

The word "flesh" carries a slight sexual connotation in English. However, there is no evidence that the author was thinking of a sexual union in Genesis 2:24. As already discussed, the verb dabaq does not support a sexual union. The noun basar also does not support a sexual connotation. Of 270 uses in the Old Testament, I believe the word is used in connection with sex in Ezekiel 16:26 ("You also played the who*e with the Egyptians, your lustful [literally "of great flesh"] neighbors, multiplying your whoring, to provoke me to anger." (ESV). By far the normal meaning is literal flesh or as a metaphor for the whole body. If either of those meanings makes sense in context (which they do), it would be irresponsible to postulate an obscure metaphor for sex. None of this, of course, means that sexuality is excluded from the union, only that it it is not the defining trait.

What then is the nature of the union? According to most commentators, Genesis 2:24 is setting up the base for marriage. Targum Onkelos agrees. In v23 we find "And Adam said, This now is bone of my bone, and flesh of my flesh: this shall be called Woman, because from her husband (מִבַעֲלַה) this was taken." The word מִבַעֲלַה means "husband" or "master", but not simply "man". It seems the Targum's author clearly has marriage in mind.

This interpretation is also backed by Malachi:

But you say, “Why does he not?” Because the LORD was witness between you and the wife of your youth, to whom you have been faithless, though she is your companion and your wife by covenant. Did he not make them one, with a portion of the Spirit in their union? (Malachi 2:14-15a, ESV)

Here, the author makes a clear allusion to Genesis 2:24 and ties it to the marital union. He continues:

“And what was the one God seeking? Godly offspring. So guard yourselves in your spirit, and let none of you be faithless to the wife of your youth. For the man who does not love his wife but divorces her, says the LORD, the God of Israel, covers his garment with violence, says the LORD of hosts. So guard yourselves in your spirit, and do not be faithless.” (2:15b-16)

Malachi thus argues that because the martial union has created one flesh, to divorce is an act of violence, a ripping apart of flesh so to speak.

Conclusion

Genesis 2:24 is about marriage. The grammar does not support reading the passage as simply a sexual union and the flow of the analogy from Genesis 2:21-2:24 suggests that a man is incomplete without a wife. This is how ancient translators and interpreters saw the passage. The conclusion is also reinforced by Genesis 2:18 which says that God wanted to create a partner for Adam because he was alone. He needed companionship, and to fill this need a being of like substance was created out of his own flesh. Man's need for companionship is not fulfilled via sex, nor does a sexual union make him complete. Only a deep relationship, united in marriage, can do that. The traditional interpretation that the passage is providing the basis for the marital union is correct.

Based on my analysis I endorse the NET translation of 2:24 as a significant improvement over most translations:

That is why a man leaves his father and mother and unites with his wife, and they become a new family.

According to Genesis 2:24, a man and a woman become "one flesh" via the act of marriage. The passage does not explicitly state how marriage is defined, but it is clear that something more than a sexual union is in mind. Instead, the author's intention is to provide a reason why marriage occurs, and his answer is that man is incomplete without woman. Marriage unites husband and wife to form "one flesh", a complete being.

St. Paul assumes the quote to be talking about the intercourse in 1 Kor 6, 16

16 Or do you not know that he who is joined to a prostitute becomes one body with her? For, as it is written, "The two will become one flesh"