The confusion with this thread, in relation to each person's understand the development of the concept of God, is that the respondents start out explaining the evolution of the concept of God in one language and, in the middle of the explanation, changes language. What I am referring to is a basic problem of semantics. In one language the concept of God comes from a synthesis of man's experiences resulting in a definition of God. This is not scientific reasoning.
In another language.the language of Plato and Aristotle, where forms representing the basis of knowing what is real, are used. As you correctly point out: "There is within man a spark of the Infinite. That 'spark' is the beginning of all values and without it, given the bestial nature of man, we'd still be chucking spears at each other...."
This observation alludes to the fact that man is born with knowledge and that learning is remembering what he already knew. That spark of the infinite is the beginning of all values which the Western World has used as the premises of all the achievements in science, medicine, art, reasoning, and religion. Correct science and reasoning can be trusted because eternal premises do not change. All physical and mental change is only an appearance and can be explained by other principles of scientific laws. For example, ice represents the form of solidarity. When ice melts and turns to water, there is no conflict in the idea that values do or do not change. Ice and water is still H20. In explaining life with changing principles is as dangerous as trying to send a man to the moon with changing the premises of science. When ice changes to liquid, it is doing so by another eternal law of science. By knowing all the scientific laws, which do not change, enabled man to go to the moon. Science did not change. It was only an appearance. Western Civilization has always depended on the ideas whose premises do not change. Evolution in the concept of God is also an appearance. God dose not change.