I recently finished Charles Stross's Accelerando, available in printed form or online in its entirety. If you have a free weekend, do read it. Stross examines some of the implications of a world in which biology and machinery increasingly diverge, and the human body rapidly becomes obsolete. By the end of the book, all the main characters are essentially digital copies of themselves housed in new bodies, with some characters making several copies of themselves at one time. The human race, such as it is, is desperately trying to stay ahead of their computerized posthuman descendants, who are relentlessly converting all the matter of the Solar System into server space.
Only tangentially does Stross consider the soul, and what would happen to it. The death of characters' original bodies is considered of no intrinsic importance; more than that, nowhere does Stross ask why the survival of humanity is important, given that humanity per se is soon replaced by perfect "personality copies" housed in artifical bodies. The biological imperative is gone; for mechanical beings, any spiritual imperative must be gone as well. So why bother?
This is perhaps the greatest gift of the approaching Singularity, and the greatest curse. Humanity is forced to confront the question that much of it has studiously avoided asking: what is our purpose? What function does humanity serve? What goal must sapient beings aim for? And how much of that is dependent on your physical makeup?
I believe that the soul is a crucial part of the human being. (I tend to associate the soul with top-down control of the brain, as opposed to bottom-up control that originates on the cellular level.) If you spawn a perfect clone with your memories, does it get its own soul or does yours split in two? Can an uploaded mind have a soul? If not, what would that mean for the dreams of the transhumanists?
Can one manipulate spiritual energies with an artificial body, or an artificial brain? For most people, the question is to all appearences academic. Yet everyone has some tie to the higher realms, whether or not it is conscious. Could that tie be severed by excessive mechanization, and would the cyborg in question still be human?
Odd as it sounds, the only way I can imagine resolving the questions about the soul and consciousness is through experimentation. (I have this image of the first hard-core cyborg standing in a big white room, surrounded by Kabbalists and Qigong practicioners scribbling on notepads…) But that does little to solve the larger questions about purpose. Such questions are way above my pay grade, of course. But I think that as our power over the body itself becomes greater and greater, the world must come to a better understanding of the spiritual so that it can better fathom what the costs might be.
This is a time of great upheaval. Those of us who live for good have an obligation to develop our own spiritual strength, for the world desperately needs a stronger flow of Divine energy. This does not mean that we should all go off to a cave and meditate for twelve years, as did R' Shimon bar Yochai; but neither can we ignore the spiritual entirely. For soon, we may be offered physical immortality, at the price of the spiritual. My intuition is that transhumans would be spiritually damaged; I hope that I am wrong, and would be overjoyed if I were. But for us to know, we must first learn what the spiritual is.