One Flesh – Is it just about sex?

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The other day, I wrote about how a particular problem at the moment is where we acknowledge that a theology of everything is possible but do this by breaking everything down into its constituent parts and analysing them leading to what I called the anatomisation of everything.

I was making a wider point but it obviously arose in the context of recent discussions about a possible theology of sex and specifically, the way in which Josh Butler’s forthcoming book takes the concept of “one flesh” and attempts to develop a theology of sex from that.  Part of my disagreement with Butler is that he is, in my opinion taking something that should refer to the whole marriage relationship and applying it specifically to the act of sexual intercourse.

The phrase “one flesh” is used in the Bible just 6 times or in fact on 5 specific occasions and that perhaps should cause us some caution before we overplay it.  Those 5 occasions are

  1. Genesis 2:24 where the author comments on the creation of Eve as a suitable helper for Adam and explains why a man will leave his family to be united with his wife.
  2. Tw uses in Matthew 19:5-6 where Jesus explains why divorce should not happen.  The two people are now “one flesh.”
  3. Mark 10:8 which is in fact the parallel passage to Matthew 19 meaning that we are really talking about four occasions.
  4. 1 Corinthians 6:16 where Paul argues that a person who has sex with a prostitute has in effect become one flesh with her.
  5. Ephesians 5:31 which quotes the Genesis 2 passage and links human marriage with the mystery of Christ’s relationship to the church.

I think that the reason why some people have been equating “one flesh” to “sexual intercourse” is because they are starting with the 1 Corinthians 6 passage.  That passage specifically describes an act of sexual intercourse.  However, note there problems here. The first is to do with theological methodology.  If we start with 1 Corinthians 6, then we start in the wrong place. In that passage, Paul takes a phrase that is already known from another context.  We should start with the original context and usage and allow that to inform what Paul means in 1 Corinthians 6. 

Secondly, we need to remember that what Paul describes in 1 Corinthians 6 is a distortion of the original intention.  God’s intention was marriage between one woman and one man. By going and having sex with a prostitute, the man distorts and undermines the nature of the marriage relationship.  In fact, Paul’s point here is that you can’t separate sex out from relationship, that sex is more than  that and so fornication is about more than a one off act, it has lasting consequences.

Thirdly, notice that even in this situation, Paul is not saying that sexual intercourse and being one flesh are the same thing. He is suggesting that the person who has sex with a prostitute becomes one flesh with her.  Now, this does suggest that the sexual act itself is significant to how a couple become one flesh but even still, that act has happened within the context of a covenant or contract between the two parties, that it is underpinned by a financial transaction, that it excludes the many crucial commitments made in wedding vows and that the uniting couple intend their relationship to be fleetingly temporary does not change that.

So, what is “one flesh” when we go back to Genesis 2 and when we see how it is then picked up and used in the New Testament passages.  Well, in Genesis 2:22, Adam responds to meeting his wife, Eve for the first time with these words:

This at last is bone of my bones
    and flesh of my flesh;
she shall be called Woman,
    because she was taken out of Man.”

The consequence of marriage union, that the couple become one flesh is founded in something that was already true of their physical nature. Eve is reunited to Adam in a new way because she was from Adam, it is because she was from his flesh that she can become one flesh with him.

Secondly, notice that the thing that makes them become one flesh is the leaving and cleaving.  Contra contemporary marriage ceremonies, the focus is less on the wife leaving her parents and more on the husband leaving his.  This leaving and cleaving speaks about the whole process of getting married right back from betrothal to consummation -and yes the consummation part has been historically significant to the question of whether a marriage covenant has been formed. Marriage and sex cannot be divorced from one another. Yes, sex is part of the question, part of what makes up marriage but marriage is about much more than sex.  This is important for a couple of reasons.

First of all it helps us to think about contexts where for various reasons, a couple are unable to physically consummate their marriage.  This might include inability due to physical health problems, or even delay due to emotional health and past trauma.  We rightly declare the couple as already man and wife at the point when vows are exchanged not after their first night together.  Or sexual union is the consequence of marriage not the cause.

The second practical implication therefore concerns what happens when someone has been involved in casual sex.  Some people have taken the 1 Corinthians passage to mean that as soon as two people have sex, then they are married.  The assumption then is that they must formalise the deed by getting the paperwork.  I think this misses the point that 1 Corinthians 6 is describing a distortion or parody of marriage. The practical solution, for all kinds of reasons to someone visiting a prostitute is not that they should then go and marry her.  There may be occasions when the wise thing to say to a couple is that they now need to prioritise getting married after starting a sexual relationship. However, there will be plenty of situations where that simply isn’t the right resolution, for example where this is bringing someone into a potentially coercive and dangerous relationship.

That “one flesh” is a description of the whole marriage relationship is, I believe, confirmed by how Jesus handles the phrase in Matthew 19 and Mark 10.  Jesus’ point is that they are one flesh because God has joined them together and this has created something permanent.  They don’t become one flesh momentary whilst in the bedroom, they are one flesh in all that they do. Indeed, if we were being literalistic about this we would have to insist that they don’t physically become one flesh in bed, even if the phrase might poetically describe the closeness of their physical intimacy.

And so, it helps us to think about what we mean by the word “flesh.”  The word can have a number of potential meanings as we see in the New Testament.  So, sometimes it describes part of the physical body, sometimes it is used to some up human nature generally and sometimes it specifically refers to the human nature in its sinful state, in opposition to Christ and The Holy Spirit.

How is it being used in this phrase? Well another two things we are not meant to get over separated are the physical body and the spirit.  So, I want to suggest that the phrase “one flesh” is not meant to get us thinking of the human body on its own. Rather body and spirit are united and so the two bodies and two spirits are united into one.  We could translate the phrase to say that “two people become one person”.  Yes, that is exemplified in their physical, sexual union but it describes a meeting of minds, a uniting of wills, a coming together of hearts.  It should have legal impliatinos that they are regarded together as one person. 

Incidentally, this also has practical implications as I argued in “Marriage at Work.” All of the stuff concerning headship and submission should not be obvious and clunky.  The signs of a healthy marriage should not be that people can see that the husband is “the head” and that his wife “submits” to him but rather, people should be able to see that they are united, that they have become one.[1]

[1] See Dave Williams, Marriage at Work (2009, Marriage at Work (, 75.

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