Can you explain the difference between the body and the flesh in 1 Corinthians 6:16?

This text is from a transcript of a talk by David Gooding, entitled ‘The Christian Philosophy of Man’ (1994).

I suspect you mean, why are the two terms, body and flesh, used in that one verse? In the context, perhaps the difference is not all that great. Paul has been talking about the body, and how the body shall be permanent—'and . . . the Lord . . . will also raise us up by his power' (1 Corinthians 6:14). He then says, 'Do you not know that your bodies are members of Christ?' (1 Corinthians 6:15).

He's not thinking of your flesh, the stuff that your bodies are made out of, but the whole thing. The flesh is the stuff that the body is made of; the body is the thing that is composed of flesh. 'Your bodies are members of Christ . . . shall I then take the members of Christ and make them members of a prostitute? Never!'

Why shouldn't you do that? 'Do you not know that he who is joined to a prostitute becomes one body with her?'—physically so. He makes a difference between someone who's joined to a prostitute and someone who is joined to the Lord. With someone who is physically joined to a prostitute, the nature of the link is flesh, isn't it? He that is joined to the Lord, the nature of the link is spirit: 'But he who is joined to the Lord becomes one spirit with him' (1 Corinthians 6:17).

The reason why 'flesh' is used in the first place is because Paul is quoting the Genesis rule: 'For, as it is written, "The two will become one flesh."' (1 Corinthians 6:16, cf. Genesis 2:24). And Adam said of Eve, 'This at last is bone of my bones and flesh of my flesh' (Genesis 2:23). They're the same material.

As I would see it, then, 'joined to a prostitute', the method of connection is the flesh. By contrast, 'joined to the Lord', the joining point is the Spirit.