Molly, the "old man" is crucified also. This is not a reference to the body but the spirit of the man inside that vessel. Do you see that? It will cease to exist.
Paul
well, I can only speak to my experience of it. But I am trying to understand what Paul is saying, also.
"old" [man]
G3820
παλαιός
palaiospal-ah-yos'
From G3819;
antique, that is, not recent, worn out: - old.
This is an interesting word. We might call someone an antique in jest, referring to his age, but this meaning conveys a literal antiquity--something that has been around for a very long time.
Everything that is primitive about us as a species derives from our bodies. We even have a part of the brain called the old brain because we have it in common with more primitive species. (We also have a part of our brain that is unique to all species of animals in the world).
Nevertheless, if there is a 'spirit of man,' I would argue that it derives from the soma--the flesh--rather than vice versa. It is certainly overridden by the soma. We want to save ourselves because the flesh wants to save itself--the flesh with its intricate systems designed for flight or fight will do whatever is necessary to live. The spirit of man, if there is such a thing, cannot override this physical system easily.
You could argue that this is a good thing. We are given fear for a good reason, for instance. Fear is a signal to us that there is danger. But, Christ tells us not to be afraid. Why? Because we cannot do what we have to do as disciples of Christ if we let the physical fear signals coming from the body control us. There are people who cannot even read something because it causes them fear even though it might be factual and very important, much less cast themselves physically into danger.
If we are a slave to our flesh, we cannot do what we have to do. The people we call heroes are those who have done what they had to do regardless of the imperitives of the-- flesh.
17For the flesh lusts against the Spirit, and the Spirit against the flesh: and these things are opposed one to the other, that ye should not do those things which ye desire; --Gal 5
That doesn't even mention a spirit of man. That says the war is between flesh and the Spirit of God.
If our spirit, arising from fleshy desires, or held captive to them, is regenerated and renewed by the Holy Ghost, then we have a new/restored/resurrected spirit, one that is not subject to the body, but subject to God. Now we have a spirit that can testify with the Spirit that we are indeed children of God. But this is a matter of walking in the Spirit of Christ rather than the spirit of flesh.
16But I say, Walk in [the] Spirit, and ye shall no way fulfil flesh's lust. --Gal 5