We disagree on Jung's premise. That's fair.
Ultimately we cannot prove outright that the spiritual drive is an inherent part of the human condition or the result of socialization. Our best tool in this case is conjecture. But conjecture can be done well or bungled horribly. I don't think either of us are guilty of the latter.
Agreed that it is hard in our society to do an experiment which might shed more light on the inherent drive/socialization issue. My position is really two points. First, while a "spiritual drive" may be very common, I don't think it is as universal as, say, parent-infant bonding. Infants don't die if they are not nurtured to satisfy the "spiritual drive". Second, many of the people who make the argument for a biologically determined need for religion (and I exclude you from this group) make a great leap from a generalized religious instinct to a very specific theology. In fact, medieval theologians made this one of the "Proofs of God"!
Consider this as well. Perhaps religious belief is symptomatic of the inherent need to socialize. I am open to this idea. Be that as it may, whether the spiritual drive is as primal as fear or the result of socialization, it is very, very ancient, and I don't know that something has to be inherent or primal to necessarily be an integral part of the human condition. Simply having been a defining part of humanity since before antiquity might be enough.
Clearly humans are social animals and do not survive without effective socialization. As this is biologically driven, religious belief could be considered one of the primary methods of achieving that socialization, which would make it a very common institutional adaptation.
No problems for the most part with your observations. However, I am not making the argument that spiritual belief is biologically determined. It may be, but I am not making that case. I am simply saying that it is a defining part of the human condition.
Another example of the human condition that is not necessarily biologically determined is the tendency to embellish. It is virtually universal. Even the most honest people in the world cannot resist the tendency to embellish, even if it is a tiny bit, a recollection of events. Even if a person tells a story as it happened, no person's recollection is 100% perfect, because we are fallible and we suffer memory loss to varying degrees and over time. The human tendency is to fill in the gaps to the best of their ability. Even the most honest person will fill in those gaps with information that is favorable to themselves or their position. This is because we all possess an ego. Some people may embellish more than others, and some may outright lie. This is why, in trials, there can be variations in what three different people testify to who saw the same thing. Each are applying their own biases and self-protection mechanisms to their recollection of events. Is that tendency biologically determined, or socially developed? It's all part of the nature/nurture argument and one that is extremely difficult to solve.
My position is that the spiritual drive is a part of the human condition in a similar way, whether socially or biologically determined, or a combination thereof.