This is going to be a “quick and dirty” history lesson because to fully do it justice would take much, much too long. So just hang on, buckle your seat belts, and if you want more info, Google will take you there. It’s bloody, brutal, and endlessly fascinating.
The Chinese tried it with their Imperial Dynasties. Or rather they had their Emperors as priest and liaison to the gods for the people. It was a duality of roles that mixed both their religion with their government in the most intimate way possible just short of declaring that the Emperor WAS a god on earth.
The Japanese did declare their Emperors to be Gods on earth up until Emperor Hirohito abdicated his throne in the 20th century. It was part of the culture that sent their men out to die in the kamikaze missions in the belief that they would be dying for the Emperor.
In Africa, the Egyptians declared their pharaohs to be gods. Consequently, there were no mere mortals good enough for them to marry so they had to marry members of their own families. The infighting among cousins and associates made for somewhat short dynastic lines. In later times, Omar al-Gaddafi in Libya to the west would declare himself a Supreme Leader and Ruler of all of North Africa. He would tell the world that he was a god. So would Emperor Haile Sailasse of Ethiopia who styled himself as the Lion of Judah or the Leader of the Lost Tribe of Israel. (Bob Marley famously had his heart sent over there to be buried next to the man when he died.)
The Aztecs and Incas, among others in South and Central America, had cultures where the priests either ruled or co-ruled with warlords. Human sacrifice was apparently commonplace. Slavery of conquered peoples was known. Life was brutal on the bottom, but luxurious on the top. The Spanish and Portuguese soldiers and priests came in and destroyed most of these civilizations in the name of their religion to take the land and the gold.
The Caucasians in Europe were not as bold (usually) about declaring themselves gods, although a couple of the Roman emperors did and one declared his horse was. Mostly it was the popes who tried to clamp down on what they saw as the rampant immorality of both the populace and the nobility. It wasn’t altruistic in nature nor was it strictly piety, although they did cloak it “in the name of God”. If the ruling nobility decided to do something remotely pious (such as traipse off to the Holy Land on a Crusade with his knights), you can bet there was more than one priest involved in telling him that it was his “duty to God” to do so. In the meantime, while he was gone, said priests would be running the country and looting the treasury among other things.
All of the countries in Europe went back and forth between Catholicism and Protestism once Martin Luther nailed his theses to the door of the church. England, in particular, had had problems since Henry VIII decided to break with the Catholic church and form the Anglican church so he could divorce Catherine of Aragon to marry Anne Boleyn. They all had “state religions” and if you didn’t go to the “state sanctioned church”, then you didn’t get business from the right people, your family was shunned, you paid more taxes, your daughters might get raped, your house might be burned down, etc. And if you happened to be JEWISH, things could get really rough. Soldiers might come and get both parents, take them off, and torture them for no reason at all. If they died, who cared? They were Jews.
In the early 1600s, the people got tired of the Catholics doing this crazy stuff, and started following a man named Oliver Cromwell who was a Protestant. The country flipped to being that for awhile. But it was worse. So in 1611, he was executed, and the monarchy and Catholicism/Anglicans came back. Be careful what you wish for.
Here in the USA, we have not been immune. We have had our share of religious people trying to tell us that politics and religion belong together. It is precisely BECAUSE of what happened to Oliver Cromwell, James II, Charles II, George I, II, III, and IV that our Founders wrote into our founding documents to beware the incorporation of religion into our government.
It’s not that we do not want men and women of high moral character in government. We most certainly do. But what we do NOT WANT or NEED is the incorporation of ONE religion above any other and the ENFORCEMENT of the practice of that religion BY THE USE OF LAW upon our citizens. It is that part that is anathema to the entire concept of democracy and freedom. That we will not stand for.