Originally Posted by MarkT 
He is held captive by the condition of physical being, and so by his physical desires. Being a physical man means we are subject to physical desires. Paul sees nothing good in himself. Why does he still covet when he knows it is wrong? He sees law breaking or sin as being something we must master. He sees our physical desire as belonging to or indwelling the physical body. Man is a creature of instinct. He spends all of his time on himself, looking after his body, and to what end? To seek pleasure. He is always seeking after his own good to pleasure. So Paul associates sinful passion or pleasure with the flesh; something the flesh wants, something the flesh experiences, which drives him to do what he doesn't want to do.
As per my previous post, I politely suggest that there simply is no basis for seeing a "physical" - "spirit" dualism in the human person. As should already be clear, such a view simply cannot work anyway if we take Paul seriously in the fine-grained details of what he actually writes. In Romans 7, Paul characterizes the "I" as unable to do good. Well, that hardly seems possible, if the "I" is a Christian. After all, even if it were true that Paul were describing the "instincts of the physical body" doing battle with the Spirit, it certainly is not the case that a Christian cannot do good. A Christian unable to do good? Please.
Again, our Greek heritage betrays us - we look at world through Platonic spectacles. For Paul, the important distinction is not "physical - immaterial", it is "old creature" - "new creature". Look at 1 Corinthians 15 - Paul describes the resurrection body as "spiritual". Does this mean it will be "non-physical"? Of course not - Jesus' resurrection body was decidedly a "physical" thing.
The Biblical worldview is fundamentally Hebrew, not Greek. And the Hebrew mind saw the human person as not divisible into a "body" and a "soul / spirit".
Why does it hardly seem possible? Do you think we are perfect? No. Satan continually accuses us of doing wrong. We do good if we keep the commandments.
Paul said, Romans 7:15, “I do not understand my own actions. For I do not do what I want, but I do the very thing I hate. 16 Now if I do what I do not want, I agree that the law is good. 17 So then it is no longer I that do it, but sin which dwells within me. 18 For I know that nothing good dwells within me, that is, in my flesh. I can will what is right, but I cannot do it. 19 For I do not do the good I want, but the evil I do not want is what I do. 20 Now if I do what I do not want, it is no longer I that do it, but sin which dwells within me. 21 So I find it to be a law that when I want to do right, evil lies close at hand. 22 For I delight in the law of God, in my inmost self, 23 but I see in my members another law at war with the law of my mind and making me captive to the law of sin which dwells in my members. 24 Wretched man that I am! Who will deliver me from this body of death? 25 Thanks be to God through Jesus Christ our Lord! So then, I of myself serve the law of God with my mind, but with my flesh I serve the law of sin.â€
I think this is pretty self explanatory. We are weak, and almost as a rule, we crumble in the face of temptation. Not that we cannot resist the devil. We can. But this world isn’t easy. The road is hard, and the gate is narrow. Now, I know exactly what Paul is saying. Sin dwells within us, that is, within our members, and we are almost held captive to the law of sin. We are sinners. That doesn’t mean we cannot do good; that’s not what Paul is saying. He is saying he does the evil he doesn’t want to do. That's different from saying he is unable to do good.
Am I to understand that you reject the soul and the spirit? Because if you do, then you have no understanding at all. Don’t just dismiss the Greek worldview. Paul didn’t. Read the prophets. What you’re saying about the Hebrew mind is kind of ridiculous. Where does that come from? Because I think it comes from Satan; it comes from those scholars you listen to.
Jesus materialized in his physical body. He also appeared and disappeared, something we can't do. He also appeared in another form to two of the disciples. And there are many instances of angels in our form; like the angels who came to Lot. So the spiritual body can materialize. That's not to say the physical body will not be raised at the resurrection. It will. But we will be changed instantly.