Why is Consensual Incest Unholy?

In previous posts we’ve been exploring reasons why the Bible  prohibits incest. Working from a basis that the union of husband and wife is a signifier of the union of Christ and the Church, we’ve seen that there is a challenge to the Biblical prohibition of incest when we encounter a “permanent, faithful, stable” brother/sister couple. If (sexual) relationships that are consensual, non-abusive, permanent and stable are to commended, how can we condemn such a relationship between two siblings. It might be argued that such relationships have high danger of producing genetic abnormalities in offspring, but then such a line of reasoning still opens up acceptance for sexual incestuous relationships where one of the partners is sterile. In this case, why should such a couple not marry?

So why does Scripture forbid incest, even incest which is consensual, and how does it’s prohibition fit into the husband/wife = Christ / Church model? I think the answer lies back in Genesis 2.

Then the man said,

“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.”

Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.

We can see that the key to marriage is not just the union of a man and his wife (to represent Christ and the Church), but also that they come from different families. Why? Because a brother and sister are already in some sense one flesh – they share large portions of their genetic code, they have (most likely) grown up together and they are (emotionally) intimate to some degree. Marriage between two such people would not be as clear a signifier of the union of differences (we are as the Church, after all, not Christ!) as bringing together two people from different families.

There is also the very clear idea throughout Scripture that salvation is portrayed as grafting into a new family. From the notion above in Gen 2:24, to the language of adoption in Rom 8:15 and Eph 1:5, it is clear that Scripture portrays the importance of the idea that salvation is equivalent to becoming a new person in a new family. For this reason, the wife is from a different family to her husband, and she then on marriage moves into his family (or specifically forms a new family) and no longer belongs to her old (in name and other ways). In the time of Jesus it was not uncommon for the wife to join her husband in his family’s house – it would have been almost unthinkable for the reverse to happen.

So we see clearly that one of the components of marriage, the moving of the wife physically and spiritually into a new family, is a sign of salvation, a symbol of how Christ makes the Church new. Incestuous relationships can never fulfil that signification, so they (like homosexual relationships in a different way) say something wrong about the saving work of Christ. An incestuous marriage proclaims spiritually that Christ does not give new life and a new identity with salvation.


28 Comments on “Why is Consensual Incest Unholy?

  1. If you want to talk about incest, then a good place to start is Genesis 19:30-38, recounting the incest of Lot and his daughters. The situation arose because of the condition of Lot’s household – in fleeing the destruction of Sodom, Lot’s wife could not withstand the temptation to look back at what she was leaving behind, in defiance of God’s instruction, so she was turned into a pillar of salt, a symbol of shame, being neither in destruction (in Sodom) or in blessing (in Hebron, where Abraham was). Actually, this is a picture of the lives of some Christians – although saved from eternal damnation by their believing in Christ, worldly entanglements prevent them from progressing in their Christian life, and they become useless to God, and thus remain in a shameful condition.

    Anyway. Without Lot’s wife, the family was now unbalanced, with no immediate hope of continuation through the raising up of more children. So Lot’s daughters no doubt took it upon themselves to gain the increase, through the most appalling means. Of course, they weren’t the first to seek increase through improper means – they no doubt learned that lesson from Abraham himself. After all, it was Abraham and Sarah who did not believe God’s promise that Abraham would gain a seed through Sarah, who then tried to produce that seed through improper means, through Hagar.

    So incest is also related scripturally to improper means of gaining an increase – that is, in the preaching of the gospel to save unbelievers from God’s righteous judgement. God’s salvation is through faith and the hearing of His word, but some Christians may be tempted to use worldly means and attractions, perhaps because their faith in God’s promises is not strong enough.

    The result of the incest would later become the tribes of the Moabites and Ammonites, who would go on to cause great problems for the Israelites when they entered Canaan, the Promised Land. According to Deuteronomy 23:3-6, these were very much a cursed race. And yet, who can deny the depths of God’s love and mercy, in that Ruth, from that cursed tribe of Moab, would one day become one of the ancestors of Jesus Christ? This shows us that even the most wretched and cursed person can, through the redemption which is in Christ Jesus, receive their full salvation and be born anew into the Body of Christ. Hallelujah!

    • Thank you David. I think you’re absolutely right, but what I’m trying to concentrate on at the moment is how incest (doesn’t) fit in to the husband/wife = Christ/Church model. How do you think the idea of false increase fits into that?

      • As mentioned by Blair above, Leviticus 18:6 and 20:17 specifically prohibit sexual relations between siblings and half-siblings. This prohibition is in the context of the practice of the pagans who worshipped Molech; as the Old Testament record shows, the Israelites had major problems with the influence of pagan practices throughout their history. By their tolerating (or the refusal of some to reject/condemn?) those practices, their situation became degraded. King Solomon, under whose reign the kingdom of Israel reached its peak, was also the one whose lust for foreign wives and his tolerating of their practices caused him to forsake God’s ways, for which he was punished and initiated the decline of the kingdom, until the Israelites were eventually conquered and taken into captivity in Babylon many generations later. A few kings tried to restore things, tearing down the altars built to idols and so on, but it never lasted, as the idol worship and heathen practices had become too entrenched by then.

        So coming back to your original point (and it’s a rather indirect route) – incest, regarded as a pagan practice, is akin to taking “foreign wives”, and therefore a violation of the holy relationship between Christ and the church. Or is that a bit too tenuous?

  2. I’m not an expert on any matter but from an ‘outside-of-Christianity’ perspective (and please do pick me up on anything that is inherently wrong about what I write) I tend to notice a lot of black and white, right and wrong, good and bad in the rules Christians follow, and in fact in all religions.

    It seems slightly unnecessary to point out that once upon a time, going on a literal understanding of the bible, incest must have taken place (children of Adam and Eve, Noah’s Ark) and that these accounts were out of necessity in order for human life to continue. One can only assume then that this was A-OK in God’s eyes and he saw this as an exception to the steadfast, black and white rule or he would have smote them ‘old testament style’ or provided an alternative.

    I suppose what I’m trying to say is; I struggle to fathom religion’s and religious books’ desire to classify everything as right or wrong. I also suppose I haven’t really answered the question posed, instead just asked again ‘Why is Consensual Incest Unholy?’. The real answer to your question is that it depends on the circumstances. God’s got an algorithm for deciding if an action is unholy and he isn’t sharing it – so the Bible had a good stab at it and decided Incest took the quick route to ‘Yes’. It’s generally correct, but there’s the odd ‘What if’ that throws it out of whack.

    • Hi Michael,

      I guess the point of this thread is to try and find a better reason for saying incestuous sex is wrong then simply, “‘Cos the Bible says so” (which I think is part of the point you’re making). What I’m trying to say here is that the ban on incest is far less to do with an algorithm from God and far more to do with what God wants sex to be about, namely, that it signifies what he has done for humans (which is what the Ephesians 5 link is all about).

      Have you thought about sorting out a proper Gravatar?

      • What I was mainly aiming at is that your title encourages a backwards way of thinking. You can’t hope to solve the problem if you think of incestuous sex as ‘banned’. Incest may be a dark shade of grey but it’s a grey area all the same, and there are clearly times when incest isn’t unholy (as I mentioned above), thus making the question ‘Why is consensual incest unholy’ redundant.

        Apologies if the confusion is arising because I’m straying off topic a little, perhaps I should stick to the discussion at hand rather than attacking the title. I just feel it’s important to consider that perhaps the reason the answer is difficult to find, is because you’re asking the wrong question.

        What’s a Gravatar?

        • I understand where you’re coming from Michael, but I’m presenting a paradigm (married sex is a signifier of the union of Christ and the Church) which, if you accept the premise, leads one to understand *why* all forms of incest are unholy. That understanding is *not* based on notions of consent, procreation or other anthropocentric arguments but rather is based on a Christology and Soteriology. In that sense it is a truly theological response to incest, not just a sociological or biological one.

          To put it another way, your difference with me is not actually that incest is a grey area, it’s actually whether you believe that married sex is a signifier of the saving work of Christ (and whether you accept the Scriptures as authoritative in the first place in order to come to such a conclusion).

          http://www.gravatar.com is your friend – Loads and loads and loads of sites (like this one) are activated to accept them.

  3. What a clever idea! (Gravatar I mean, not incest).

    Accept the premise? By that means we may as well argue ‘Why are all cats evil elephants?’ so long as we accept the premise that all cats are elephants. Reading your original post again, I realise that you did state this acceptance at the beginning , but before that you write, “reasons why the Bible prohibits incest” – to which I am saying, the Bible must be wrong, as God doesn’t prohibit incest.

    My argument is void of anthropocentricity, yours is not however, for it is based on a human-written book!

  4. Ohhh nooo… what happened to my comment? I spent good time grafting that reply! :( I think I forgot to type in the captcha…

  5. If the Bible is the word of God then God must be contradicting himself (assuming there is an outright ban on incest written in the Bible – I am presuming from your earlier posts that there is) because in the past he has allowed incest.

    I don’t see it being beneficial to get into this kind of argument, and I apologise for straying slightly amiss of the topic’s original point. I understand that discussing the issues posed by the bible in modern life is ‘good sport’, so to speak, but from what I can see something is contradicting itself here, or someone during the arduous process of writing and translating the Bible has made an error – so what’s the point in discussing something that’s wrong to begin with? Perhaps a topic for discussion somewhere down the line? How to interpret the differences between Old and New Testament (the radical change in God’s behaviour, the change from Judaism to Christianity and how that fits in with Christian beliefs that are based around Judaism etc.)

    I am happy to continue this discussion on this thread through if you don’t mind, I was just conscious of your time, your other readers and the relevance.

    • I don’t have a problem with carrying on this conversation – after all it’s what I’m paid to do. But do you want to take it “offline” – coffee next week?

      Also, you keep falling into my spam trap – what is it about your email address?

    • Hi Michael,

      just to butt in here (as everywhere else in this thread!) – there is an outright ban on incest in Scripture. It’s at Leviticus 18:6.

      Just to say as well, I agree with your argument above Peter. And if I’m understanding what you said in a previous reply there is a point in discussing something that practically everyone agrees is forbidden – it’s that finding a good rationale for why this kind of incest is wrong may throw light on other things, and be part of a coherent theology of sex (which I take it is your hope here?). What interests me (unsurprisingly) is when people link incest with homosexuality, their reasons for doing so and what’s implied by the way they compare the two. I’m not sure that there is a link, or if there is, what it might be… wondering if it’s worth adding here (linking back to something on the previous incest thread) that the civil partnership legislation uses the same ‘prohibited degrees’ of relationship, as marriage laws do. This could imply that prevention of birth defects isn’t the only / main rationale for the law banning incest, couldn’t it? As I said on the other thread I’m not saying that simply to make the law a moral arbiter but because looking at the rationales for prohibitions like this, can be illuminating in itself.

      in friendship, Blair

      • Hi Blair,

        Yes, the purpose of posts like this is to slowly construct a coherent theology of sex based not in natural law but in Christology and soteriology.

        I think you make an interesting point about how the Civil Partnership prohibitions mirror the marriage ones, but then I wonder whether that’s simply a by-product of CP law starting with the Marriage acts and being based upon them.

  6. Dennis Prager (an orthodox Jew) talks about holiness (Hebrew – kaddash) means separateness. The issue with incest or homosexuality is that there isn’t the necessary separateness to be holy.

    This is what the bishops of New Jersey said: “Intimacy is a holy place within every human being; an innermost sanctuary where we develop our ultimate beliefs and values, nurture our closest relationships and maintain our deepest commitments. No one has the right to disclose that intimacy for someone else without consent. Such a violation is tantamount to the desecration of a sacred space. It is, in fact, a sacred space. It is the territory of the soul. ”

    One can apply the words of these two men to consensual incest which yields reductio ad absurdum.

    • Hi Eusebius,

      two things:
      1) I like the bishops’ words that you quote, but i don’t see how they forbid same-sex sex (or am i misreading, and that’s not one of your purposes in quoting them?).

      2) Am interested to know on what basis an observant Jew would say, re homosexuality, “that there isn’t the necessary separateness to be holy”. Rabbi Steven Greenberg has made the point that, given there is no prohibition of sex between women in Torah, it isn’t homosexuality that’s the problem for the text – i.e. it’s not the sameness of sex that’s the concern. Just wondering how you’d respond?

      in friendship, Blair

  7. Eusebius, while what you say is true (so long as we assume holiness to correspond to separateness), it doesn’t work for incestuous couples (like the Irish couple) who did not know they were related. It could also be applied to a couple who had known each other their entire lives – there is a greater emotional connection between many friends than between family. If on the other hand you are talking about genetic separateness, I feel it should be understood that many siblings are not closely genetically related – and only slightly more so than two randomly chosen members of an old population.

    Peter, that sounds good, but I feel I would struggle without being able to constantly check google define for explanations for your complicated words (I especially like ‘anthropocentric’) so I’ll bring my smartphone. Finding a time and date when I’m not busy may present a challenge but I’m sure I can find a slot (as it is half term) when we can meet up.

    I don’t know what’s wrong with my e-mail , surely gmail is perfectly acceptable!

    • This is a very strangely crafted sentence that alludes to a very poor understanding of genetics: “I feel it should be understood that many siblings are not closely genetically related – and only slightly more so than two randomly chosen members of an old population.”

      You may “feel it should be understood”, but I hope that everyone knows that it is false. Two siblings share, on average, 50% of genes (unless maternal twins, who share 100%). Half siblings share 25%, on average, first cousins 12.5%, etc., rapidly falling numbers. Now, the actual alleles depends on population genetic variability. There are some genes that basically show no population variation, thus all would have this gene regardless of consanguinity, but others show wide variation. It is a chip shot to a geneticist to show that two DNA samples are from siblings and two are from non-related sources. It is the same as proving paternity (father/child share 50% of genes), and that is very, very accurate.

      Then we have this the allusion to an Irish couple who were apparently siblings but didn’t know it. Even the pagans condemned Oedipus’ relationship with his mother despite his ignorance of his relationship with her. Can we commit sin in ignorance? Of course. I do it all the time. ;^) Incest in ignorance is still sin.

      • Sorry I only just saw this reply Eusebius. I don’t know where you got that information from… there are any number of millions of combinations of alleles that two siblings can possess, they are certainly not 50% similar.

        I too will comment on the oddity of your sentence ‘crafting’; two siblings will share 100% of genes unless they are of a different species, it’s the alleles that differ. In which case, we’re in the realms of beastiality rather than incest. I will take the high road and assume that was a mis-type rather than assuming you have a ‘poor understanding of genetics’. My point was, if you take an ageing, isolated population and observe two seemingly unrelated people – they aren’t cousins or second cousins or third cousins once removed – there will be great similarity in their alleles because there are few new people moving into the area to add to the gene pool. The same alleles get passed around until the the population ends up micro-evolving. It’s called the pioneer effect. A similar thing happens when a natural disaster wipes out a lot of an isolated population. It’s called the bottleneck effect. You would not condemn, however, an isolated population that is a prime example of both these genetically restricting conditions for reproducing, but you would two siblings! You certainly wouldn’t make it illegal, yet it is no more/less detrimental than incest.

        ‘Even’ the pagans? Are we now assuming they’re some kind of lesser life form that cannot distinguish between right and wrong? You may well be able to commit sin in ignorance, but that doesn’t explain why incest is, or give justification for it being a sin in the first place, which is what we’re trying to discuss.

        @Blair (from many posts ago – only just read it) – I am not saying that discussing this is pointless – far from it, what I am saying is, discussing incest from the start point that it IS unholy, rather than IS IT unholy, will lead us quickly into a playground full of swings and roundabouts.

        Apologies everyone for the lateness of my reply to the posts, I didn’t mean to ignore them but I think the order they appear on the thread (due to the spam filter maybe?) means I didn’t see them when I came back to post again.


  8. Both the natural law and God’s law conflict with both incest (likelihood of recessively inherited diseases, traits) and homosexual relationships (sterile, diseases, physical injuries). Emotional, physical, relational and societal harm is consequent and is usually found to be a precursor to all sin (which is an violation or trespass of God’s law in heart attitude, thought, word and deed.)

    • Um, Anna, heterosexual relationships also can be sterile, transmit disease, and cause physical injury… this doesn’t look like much of an argument against same-sex sex to me…

      in friendship, Blair

  9. The natural and spiritual are both God’s law and commandments and both are violated…the earliest of which is ‘be fruitful and multiply’ or flourish and multiply. Both incest and homosex are rebellions against this commandment.

    Spiritual damage and evil spiritual infection is also consquent to sin, opening the door to an increasing evil influence, thoughts, actions, upon self and others.

  10. Consensual incest can allow people to ‘be fruitful and multiply’. There’s no reason why a brother and sister can’t produce perfectly healthy children, both emotionally and physically.

    • Totally true, so “consent” doesn’t provide a good reason why it’s unholy. A Christological and soteriological critique does (get your smartphone out for that)!

  11. Just catching up on a huge backlog in my Google Reader after a fortnight away.

    “In the time of Jesus it was not uncommon for the wife to join her husband in his family’s house – it would have been almost unthinkable for the reverse to happen.”

    But isn’t this “unthinkable” thing exactly what Jesus says in Matthew 19.5: “‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’?” What do you think is the significance of this?

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