A former student who is studying theology wrote not long ago to ask my opinion on the nature of the soul. I'm not a theologian, and I freely acknowledge that my guess is no better than anyone else's, but rushing in where wise mean fear to tread, this was my reply:
Some people think of the soul as a sort of "ghost in the machine", as Gilbert Ryle dismissively described the dualistic view of mind. Some people identify the soul with the mind. Some say the soul is our personality plus our body. In other words, for them the soul is the entire self.
It certainly could be that any of these is indeed what our soul is, although I think that if we include the body in the concept we run into a difficulty since bodies age and deteriorate. We might wonder whether our soul is what we are at ten years of age, or seventy, or at death. Despite the difficulty, however, I'm not discounting the idea.
My own view, though, is that our soul is really the totality of information which describes us: our personality, our life history (whether remembered or not), our values, knowledge, character, aspirations, etc. This information is not "in" us in any way, but rather it resides in the mind of God, like a file in a vast database, and is thus eternal. When our bodies die, this information, or at least some of it, is instantiated in another format (a body or body-like entity) in another world so that we are capable of experiencing another existence. We can think of it as a kind of download of information which creates the phenomena of "body" much like the software we load onto our computers creates the images we see on our screens.
This view is compatible with both materialism and substance dualism since regardless of which, if either, is true it has no bearing on the existential status of the soul. If it should turn out that mind is just the word we use to describe the functioning of the brain then the existence of the soul is no more jeopardized by that discovery than if it turns out, as I think it would, that the mind is something related to, but other than, the brain.
Even many materialists would acknowledge that a complete description of every person exists, although they could certainly add that the description is inaccessible and useless. They would doubtless point out that such a soul only exists in the same sense that numbers or logical relations exist even if there were no minds to apprehend them. They would exist but be utterly useless. The set of propositions which gives an exhaustive description of someone still exists after a person's body dies but would only be useful if it could be somehow conjoined with consciousness and another "body" of some sort. The possibility of this happening most (though perhaps not all) materialists would deny.
On the other hand, if there really is an omniscient God, then when my body dies, all is not lost. I, the set of propositions which describes the essential me, the information that comprises my identity, continue to exist in the mind of God. I may have no conscious awareness of my existence, it may be like being placed into a deep coma, but I exist nonetheless. I am not gone. If and when God decides to download the information (or the greater part of it) to some "body", the file marked with my name and containing a complete description of my self, infused with a spark of consciousness (mind?), becomes a revivified person. At that point I will have been resurrected, returned to life.
This has been the grand hope of Christianity and other theistic religions down through the ages, and it is this hope, this opportunity, that God held out to the world in prototype on the first Easter when He raised Christ from the dead.