In First Corinthians 6.12–20, Paul begins:
‘All things are lawful for me,’ but not all things are helpful. ‘All things are lawful for me,’ but I will not be enslaved by anything. ‘Food is meant for the stomach and the stomach for food’ – and God will destroy both one and the other.
‘All things are lawful for me’: this is of course a reference to Christian liberty, but the licentious Corinthians are also abusing this concept by appealing to it in a worldly way, a way that probably makes reference to pagan custom, like Americans who say, ‘It’s a free country!’ and really mean that they don’t want anyone telling them what to do. Thus, Paul doesn’t deny the quotations themselves, but he brings the argument back toward the gospel: the gospel is a message of life, of freedom from the bondage of Satan, so ‘all things are lawful’ the way the Corinthians are meaning it is a parody of the message of Christ.
Again he quotes sentiments they undoubtedly must have expressed, sentiments that sound good but are said with sinful intent: ‘food is meant for the stomach and the stomach for food’. Quite so, Paul seems to agree: the body does have a real and legitimate sexual appetite. Yet he reminds the Corinthians that in the flesh all will perish, and Man who is from dust will return to dust, and all in Adam will die like Adam, but that in Christ we are come to an indestructible New Creation. Thus he sets up for a flesh-spirit distinction between the old order of Adam and the new order of Christ.
His next words seem to form a chiasm:
A. The body is not meant for sexual immorality, but for the Lord, and the Lord for the body.
B. And God raised the Lord and will also raise us up by his power.
C. Do you not know that your bodies are members of Christ?
C′. Shall I then take the members of Christ and make them members of a prostitute? Never!
B′. Or do you not know that he who is joined to a prostitute becomes one body with her?
A′. For, as it is written, ‘The two will become one flesh.’ But he who is joined to the Lord becomes one spirit with him.
The first half of the chiasm is about creation, the order of the cosmos. First, all things are for the Lord, and the Lord affirms the body and the goodness of what he has made: this is especially true of the New Creation, in which the Lord Christ is also given for his Body. Second, Christ has been raised from death, and so will we, because he is one body with his holy Church. Third, this is because our own bodies, for us who are in the covenants of the Church, are members of Christ.
In the second half of the chiasm, Paul emphatically denies that we should let the members of Christ be made ‘members of a prostitute’. To reflect the last part of the chiasm’s first half, he speaks first about individual members (implying ‘you’): he absolutely rejects the idea of making people members of a rival body, a body of adulterous apostacy from Christ. For he who is joined to a prostitute in sex becomes one body with her: this is a way of death, against the resurrection promised in the first half. This is an illegitimate use of two becoming one flesh, contra Genesis. He who is joined to the Lord, on the other hand, is part of him by the Holy Spirit, not by the flesh of Adam.
By speaking this way, Paul has framed the whole prostitution matter in terms of Adam-flesh versus Christ-Spirit, in terms of old, corrupted creation versus new, redeemed creation which will renew and cover all the earth. It’s true that prostitution breaks the one-flesh union of marriage between a man and a woman, but more than that, it breaks an even closer connexion between the fornicator and the one spirit of Christ with his Church – for the point here is in fact about apostacy, not simply what we designate as ‘sex’. For this reason, he can conclude,
A. Flee from sexual immorality.
B. Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body.
Or do you not know that your body is a temple of the Holy Spirit within you, whom you have from God?
B′. You are not your own, for you were bought with a price.
A′. So glorify God in your body.
In glorifying God in our bodies, we must flee from sexual immorality. Paul compares sexual immorality to sinning against the body with which believers have been bought with a price, i.e. Christ’s physical body, which is our own body if we are part of the same Body with him: this is because sexual sin is, more than every other sin, attached to our body when we do it. In the New Creation, our bodies are animated by the living Spirit as well as by natural flesh, so this sin is totally against the nature of that to which we’re redeemed.
Thus we’re called to avoid fornication, to the glory of God in our body (and in his Body). Glory, of course, is what characterizes the New Creation, where the Church is the glory of Christ as a woman is of her husband.