Once again, I’ll move this out of comments on to the main page.
Because I’m wordy.
“You were surprised that such a bright student could hold a Gnostic belief; but does it really make a practical difference in that person’s–or any other person’s–life, especially since it’s just one out of a panoply? It seems, especially to an outsider, like such a minor heresy in the grand theological scheme of things. If you had never asked, would you have guessed?”
Again, the point of the “resurrection of the body” is that the whole person is redeemed. Christian doctrine also teaches that this “redempted life” of ‘heaven’ is available to us now, through the Spirit (see “already, but not yet” soteriology). Christian ethics can be summed up as “living the life of heaven now.”
If sanctification is “learning to live the life of heaven” and this life is corporeal, then our very sanctification is insufficient if not also corporeal (“offer your bodies as living sacrifices”). How does this play out in the Christian’s life?
1) Worship: The historical Christian church has always incorporated movement in their corporate worship services. Also, “sensory input” (I’m not sure what the word would be) has played prominent roles in numerous traditions (see incense, icons, rosaries, etc.). A Christian that does not think the body important will neglect the richness of these aids.
2) Disciplines: The historical Christian church has also advocated “spiritual disciplines” as means of developing one’s relationship with God. Ironically, these “spiritual disciplines” are often very physical (see fasting, solitude, silence). Personally, I experienced a much richer prayer life once I began praying on my knees and have also experienced significant spiritual growth while fasting. If the body is not viewed as an intrinsic part of our salvation, then it is difficult to see why these disciplines would “work.” Yet I have the testimony of 2000 years of Christian tradition (and personal experience) informing me that they do.
3) Sexual ethics: See 1 Corinthians. This was the whole problem. They didn’t consider the general resurrection to be physical and subsequently thought they had license to act (sexually) however they wished. This was also Jonathan’s point in the comments to my first post.
Are those specific enough? I could give a more specific outline of the role of the body in (specifically) Pauline theology, but these seem to be some of the many applications. I’ll sum up: if salvation is body and soul, that has ramifications for sanctification. If a Christian does not affirm the former doctrine, then they will not adopt certain methods for the latter. Hope this is helpful.