The Ancients were not ignorant of monotheism, but as they had no distinction between culture and civics, it equated with authoritarianism, as in one god, one ruler.
Democracy and republicanism originated in pantheistic societies, which were the original multiculturalism. Many gods, many factions.
The Roman Empire adopted Christianity in formalizing its function as a political entity, rather than just a cultural center. Though it retained vestiges of pantheism, with the Trinity.
As such, it laid the cultural foundation for monarchy. Divine right of kings.
It was when the West went back to those more populist forms of government that separation of church and state, culture and civics, became necessary.
The logical fallacy of monotheism is that a spiritual absolute would be the essence of sentience, from which we rise, not an ideal of wisdom and judgement, from which we fell.
That we are aware, than the details of which we are aware.
Conflating the ideal, which is aspirational, with the absolute, which is elemental, creates the presumption that one's aspirations should be universal, rather than unique.
This assumption permeates many of the belief systems, ideologies, movements, political parties, etc, that have sought to replace monarchy and even monotheism.
The reality is that good and bad are not some cosmic conflict between righteousness and evil, but the basic biological binary of beneficial and detrimental. The 1/0 of sentience. What is good for the fox, is bad for the chicken. Even bacteria get it.
All the higher order social contructs and connections; love, honor, trust, respect, responsibility, etc, emerged and evolved out of lower order structures. Consequently when good is treated as aspirational, rather then elemental, conflicts do become a race to the bottom, of us versus them, good versus bad. As all nuance and subjectivity is suspect.
So rather then such situations causing social relations to evolve further, they lead to break downs.
What allows nature to be so diverse and dense, is that it is not a monoculture.
