If we don't survive the death of our bodies, then we have no hope in a resurrection.
Some people say that if we have souls that survive the death of the body, then there's no need to have a resurrection, and if we have a resurrection, there's no need to have a soul that survives the death of the body. It seems to me, though, that unless we have some immaterial aspect of our nature that survives the death of the body, there's no hope for a resurrection at all.
Before God can raise a person from the dead who has completely decomposed, God must have perfect knowledge of that person. His knowledge of that person must serve as the blueprint for bringing the person back. But God's knowledge of us is just as perfect before we die as it is after we die. He could, then, in theory, construct a body identical to ours and even implant all of our memories into the brain so that the new person would not realize he just came into existence. If God made a perfect replica of me--mental states and all--then the replica would think he was me. He wouldn't be me, though, because I'm me, and one person can't be in two different places at the same time. No matter how identical God's new creation is to me, we are still two different individuals.
Suppose God created this replica after I was already dead. He raised a new body with all the mental states and memories of me. This raised person would identify himself with me, thinking he is me. But would he be? No. If he's not me before I die, then he's not me after I die either. Me dying has no causal influence on who the replica is. It's still a replica of me, and not me myself. It doesn't matter when the replica is made; it's still a replica.
It would seem that once I'm dead, if I cease to exist, I can never come back into existence. Any supposed coming back into existence would be no different than creating a replica. Though the replica would not know the difference, it would still only be a replica. If I am to have any hope that I myself will be raised from the dead, I must survive the death of my body. There must be something immaterial about me that maintains existence between death and resurrection, and whatever that immaterial thing is, it constitutes my identity. It is me. Sounds to me like a soul or a spirit or something.
But, a person may argue, suppose God raises the exact same body you died with. Would we need a soul in order to maintain identity between death and resurrection if that were the case? I'll save that for another blog.
If you're interested, I had a discussion on a message board a long time ago with some Jehovah's Witnesses on this subject. In their view, we don't survive the death of our bodies, and we're not raised in the same bodies we die in. That creates some identity problems for them. I argued that if their view is true, then none of us have any hope in a resurrection. Here's a link to that discussion.
Another source you might want to check out is Risen Indeed by Stephen T. Davis. It's highly interesting, although he disagrees with me that a spirit/soul is necessary to maintain continuity of identity between death and resurrection.