If the concept of a deity is so abstract how could man's earliest ancestors accept it's reality..?

Question

to compel one to believe in it? How could early man believe in such an abstract concept of a god when their understanding of the reality was primitive, say barely above that of animals that survive on instinct?

Answer 1

Primitive understanding of reality caused it.  It's much easier to explain the movement of the sun through the sky by saying "the gods did it" instead of "the earth revolves around the sun and simultaneously spins on its axis, causing the sun to vanish from view for several hours a day, and seem to move across the sky"

Answer 2

...because the idea of death is even more abstract. People are always looking for explanations for things they cannot comprehend.