Primitive man had no understanding of nature. Remember, long before science the human brain could not fathom the laws of nature. It must have been very frightening to witness something like an eclipse of the sun when day turned into night and you can only imagine the sheer terror wrath by a devasting earthquake or other major natural disaster. Unable to explain these natural phenomena, man looked towards the heavens and thought there must be a being or creature responsible for these occurrences and they believed that if they could somehow appease this thing that perhaps they might be spared a calamity. Thus it was through fear and ignorance that man created god.