I agree with
@Silmarien in that I cannot see how, from a strict materialist viewpoint, consciousness is even possible. For everything would be wholely dependant on membrane potentials upheld by sodium and potassium exchange in neurons, which are determined by oncotic pressure, osmolality, membrane channels, etc. It would be very complex, but determined by previous situations within the brain and by external stimuli. There is no way that I can see, for it to arise, so consciousness would be a delusion of autonomous brain processing then.
Some form of negative feedback loop would be required to learn from past behaviour or determine action - not dissimilar to the immunological defence mechanisms or homeostatic control mechanisms. This is perfectly possible, although not even close to being found as of yet, but this cannot entail conscious thought or free action as such.
This would be the position of AI as well. There is a reason people espouse the Turing test, as that is the only way we would be able to affirm 'consciousness'. If it appears conscious from our subjective sense, we assume it is - but we haven't shown it to be, nor determined a physical way it may be. Complex programming would certainly be able to fool us, even to allow programmes to make novel changes or adapt to circumstance, but that hardly equates to 'Consciousness' as such.
The Emergent Property argument I find even more fuzzy. It is a cop-out, to say we can't explain how it is possible materially, or even a broad outline how it may do so, but because it is present, it must do so. This is at best wishful thinking, at worst a petitio principii.
I find it strange too that they are so ready to ascribe emergent properties to organised systems of electrical discharges and potential changes in brains, but would completely dismiss it in far more complex electromagnetic systems, like the Sun. If consciousness is an emergent property of neural physiology, then I see no reason why we can't conclude the Sun to be conscious as well. That is the danger when reaching conclusions based purely on preferred suppositions.
People are willing to go far beyond our data on this question, for some reason. To give some perspective, we can't even explain how breathing is controlled, let alone complex ideas like consciousness. We have located medullary and pontine respiratory centres, that if damaged stop spontaneous breathing, with some sort of pacemaker ability (how exactly we don't know). We know central and peripheral chemoreceptors modulate breathing, via partial pressures of oxygen and carbondioxide and pH. However we cannot even explain in what way we increase respiratory rate during light exercise, where partial pressures are unaltered and lactic acidosis has not yet set in; nor how anaesthetic volatile agents depress volumes and rate of breathing. This is a simpler system - we know where the respiratory centres are, we know how all the nerves run, we know how breathing occurs with pressure changes in the chest, yet we cannot more than superficially explain that. Now people want to tackle something as complex as human consciousness, our very selves, on such limited understanding and frankly guesswork of which nerve is associated with what. It seems silly indeed. This remains a philosophic enquiry, as our physiological understanding is not even close to shedding much light on this.
To the OP:
@cloudyday2, my wife has proposed something similar to me in the past. That some people are born without souls, that are mere automatons.
The idea that no one has one, but it is only created later through faith, has too much of an autosoteriological bent for my liking.
If we adopt the idea of 'living nephesh' vs 'dead nephesh' and a 'ruach' of the OT, a plausible defence for it could be given, as even your use of the parable of the Sower is quite ingenious. It does throw up as many problems as it solves, such as if the soulless would be my "neighbour", be moral agents, or be anything more than animals. It directly contradicts centuries of moral teaching and could easily be manipulated into an Us vs Them mentality, that would allow us to be very clever Devils and excuse quite a lot of egregious acts.
It begs the question of their evil acts being determined by God, or consequences of the Fallen world. It undermines retributive justice, and the concept of the Incarnation. For Christ died for the sins of men, but the concept of sin can only become operative once an existence juxtaposed to God is evident, so how are sins then 'forgiven' on receiving the faith?
No, while interesting, it seems a bit incoherent to my mind, and like all good heresy, undermines Christian Soteriology far more than it fixes a perceived problem with it.