If you want to think about “God” in simple evolution-of-ideas terms, then the stages would run something like the following. At first, humans believed all Nature was alive and that all living creatures possessed an “anima” (spirit, soul). Later, seeking to appease these powerful natural forces, people “personified” them as “gods.” There were many things that could go wrong or right in life, so there were many gods. Build temples, offer sacrifices, and hope for the best. Then they refined this polytheism into each city having one particular patron god or goddess, along with the others. That deity lived in a temple in the particular city that s/he protected. Participation in religious rites figured as an important duty, rather than as a choice. The deity didn’t move around. Greek and Roman religion were merely stems from this stock, but elaborated non-religious ethical systems of great power. Animism yielded to Polytheism.
After a while, what became Western civilization diverged from this broad cultural pattern. The Hebrews developed “ethical monotheism.” That is they believed that only one real God existed; all the others were false gods. That God existed everywhere in the world, rather than being bound to the confines of some runty city-state. That God had made a “covenant” with His “chosen people.” He would protect them if they worshipped only Him. He didn’t settle for mere rites and offerings. He also required adherence to a moral code of action in this world. Then Christianity emerged from Judaism by opening the “covenant” to anyone who would profess the faith and by extending the “covenant” to include a promise of life after death.
If you want to go all sociological-psychological, then you might argue that Christianity amounted a generational revolt by young men against the old men who ran Judaism. Alternatively, you could argue that God now wanted all of His Creation to share in the benefits and strictures of the faith he had granted first to the Jews. Polytheism yielded to Monotheism.
Then, in the 7th Century AD, another monotheistic faith arose: Islam. This, too, is an example of ethical monotheism. If you want to go all sociological-psychological, then you could argue that the Prophet Muhammad borrowed much from Judaism and Christianity, and then preached his new faith to the polytheist Arabs at a critical moment in their history. Alternatively, you could argue that God had gotten fed-up with the inability of Jews and Christians to follow His instructions. He had sent Muhammad to call back the whole world to the benefits and strictures of the faith he had granted first to the Hebrews.
Since then, Judaism and Christianity have divided between growing secular majorities and shrinking “fundamentalist” minorities. Islam, however, has not followed the same path. The Koran remains the unalterable Word of Allah.
“Every schoolboy knows” the term “a willing suspension of disbelief” when approaching a work of fiction. What might make understanding between faiths easier would be a “willing suspension of his belief” on the part of the individual.
 For a serious, accessible, and sympathetic portrayal of this belief system, see Brian Moore, Black Robe (1985).
 I suppose one could think of this as either bribery by the people or extortion by the gods. Living now in a more secular age, it appears that politicians have become the new source of manna. Reading the New York Times and the Wall Street Journal in parallel each day, I conjecture that Democrats believe in the bribery interpretation and Republican believe in the extortion interpretation. But what do I know?
 If not of universal compliance. That’s one of the things that makes Ancient History so much fun.
 I stole this from Eric Ormsby, “Allah: A Biography,” WSJ, 17 January 2019.