Very Interesting Essay!
Theologians have argued for eons (literally) as to where the soul exist within the individual; many have claimed the heart to be the seat of the soul while others claim it is the brain and other still suggest it is a shared position between the two. Then we have the more metaphysical idea of the soul existing outside the physical body within the Aura, but has tethers attached to the primary chakras; this being how the Universe feeds us the energy that allows us to be aware, sensitive and "connected" to the ALL . . . the mystical and elusive IS some have called "God" and/or "Goddess" for centuries.
Whether the soul can be proven within the parameters of current science is quite questionable at best, even with the advent of Quantum perspectives. Yet, it is Quantum Physics that presently lends to us the greatest probability of proving out such a thing alongside other phenomena that is allied with the soul & spirituality i.e. Psychic abilities and even the phenomena of Ghost or postmortem continuance on the terrestrial plane (different dimension but same horizon, so to speak).
To be "Soulless" is quite possible; our modern culture proving out such realities on a daily basis, as we find the cold-hearted and self-obsessed quite literally walking on the backs of others and oddly, not always aware of the fact that the do so. One side of this can be found within the auspices of Atheism/Agnosticism but in truth, when one breaks things down from the philosophic side, such people tend to host the peace of mind and heart the majority of us who walk the paths of mystery & enlightenment, seek. Not all such people manifest this truth, but many do. Many are unfortunately vindictive in their attitude; their Atheism comes with a large chip on their shoulder in that they are angry at God and the institutions man has built up around an apparent lie. I more than understand this venom in that I too share a loathing towards all forms of organized religion; they are all false in that man has given them structure and tangible status and as such, mankind has made carnal that which is natural, free, and accessible to all; there is no need for clergy or temples or sermons or tithes, just independent acts of introspection and conscious evolution on the spiritual level of understanding & awareness.
So no, one needn't be an "Atheist" to be soulless but one will be regimental in attitude and insistent when it comes to his/her pragmatism, carrying it to a cruel extreme. We see a considerable abundance of such attitudes amongst the master statisticians & mathematicians and even physicists and Yet, we likewise find those of strong spirit, maturity and spiritual peace because intellectualism, contemplating and acts of genuine thought (vs. thinking) allowed them to find harmony between the analytical and the metaphysical. So again, we find that true soullessness cannot be sat within the niche of intellectual thought and theory nor that of the scholastic mind. While you may find the zealot that evangelizes from this position, they are the exception and frequently found to be false when viewed by their own peers.
What we do find in these two particular areas however, is how philosophic zeal and related dogmacy robs the individual of his/her heart and how many take but the smallest seed of supposed logic and use it to justify prejudice and ridicule; antics & actions that mirror the very people they loathe and distrust. In this we find those that have at minimum, suppressed (buried) their soul into the depths of their psyche in the hope that they may never be faced by it and their humanity, ever again. The tortured soul is what results and though it knows little other than bitterness, it is not completely without a soul but rather, one that is hidden and misplaced as the result of immaturity and fear. Ironically, this same condition exists amongst "believers" as well as the non-believer in that it is the same type of prison -- an existence with blinders firmly glued in place and a myopia brought about by personal arrogance.
The truly soulless is demonic by its very nature. It does not strike out with evangelic zeal nor will it deliberately challenge others based on faith or science. No, this creature has little to no sense of connection to the ALL, or perhaps we should say "the light" in that what they do and live for is certainly dark. They see their fellow human being as tools and pawns via which they are able to obtain power, position and carnal trappings. In parts of the world such a heartless being would be seen as a "Demon" -- a human being without compassion or empathy that sees the world as something to exploit rather than protect.
Yes, we are looking at the collective conscience found in numerous Fortune 1000 businesses as well as members of those ultra-wealthy families that believe it their birthright to suppress the poor and exploit the working class however possible, draining them of their hope, income, and life-essence.
The soulless are few and not always beings of extreme power and fortune in that a fraction of them are simply the damned incarnate -- the sociopaths and predators of society who thrive on acts of cruelty be it the criminal on the streets or the "father" behind closed doors.
This is something for which much consideration is required.