Tom Holland in Persian Fire discusses Darius.
It seems he invented the idea of fighting for one's god, and that he was god's representative.
Seems to have been successful! He did run an empire!
Roll on a few hundred years, and Constantine uses the same ideas.
But this time it has a further iteration.
There is an infrastructure of buildings and office holders and rituals and rules. Stuff becomes internalised. People are self policing, with assistance, like the stazi, from family, regular attendance at ceremonies and rituals. Concepts of heresy are introduced, with reward and punishment systems.
Roll on a few more hundred years and there is another iteration. This time based on a short holy instruction book.
This one might be a deliberate propaganda tool to get people to fight an enemy, possibly invented by Romans to attack Darius's lot. But the weapon is more successful than is envisaged, and leads to new empires.
Humans have always had issues about social control - some half million year old skulls have been found with very probable evidence of murder.
"Paganism" doesn't really help run empires and cities. It is quite good at town and village level, as the Celts showed.
External policing and armies help with cities, but internal policing, schools, ten commandments, religions are very valuable tools.
The idea of "religious trauma syndrome" shows how religions are effective means of social control.
But one god systems are what empires need! They are like high grade motor oil in high performance engines.
I am unaware of discussion of religion as a successful form of social control. There are plenty of attacks on the specific beliefs and practices, but the tradition of Durkheim seems to have got lost somewhere.
If religions have functions in tribal systems, why do not one god systems get equal analysis?
Are not religions really propaganda tools? Maybe one current example is a more powerful example?