You sound as high as the people who you claim don't exist.
over 500 years BEFORE christ was born the greatest civilization in our history that dominated half of the known globe already florished.
They had democracy, representative republic, Laws against murder, stealing, raping,ect. They even had indoor plumbing.
These aren't christian ideas, they are human ideas.
You are a bit wrong on your conclusion.
The Romans had a stable society BECAUSE they had (for the times) a halfway decent religion that they mostly all agreed upon and morals from that religion guided and shaped society, helping form the principles of law and order and public behaviour.
You could read about all the whys and such in "Discourses on the First Decade of Titus Livius" by Niccolo Machiavelli.
It would be a good read to help you understand the fundamental role religion has, does and will always play in shaping and stabilizing human societies.
If you have a somewhat decent religion that your society gets it's morals from, you will have a somewhat decent society.
If you have a bad religion, then you get a bad society.
If you try to actually have no religion, you then wind up very quickly with the straight out law of the jungle and survival of the fittest which is why it's not done ever.
You'll never have no religion, religion is innate to humans, it has always existed throughout human history and guided societies.
The Atheists who claim to have no religion, when they get in power make a new religion out of worship of the state with almost all the same trappings and many of the same morals they claimed to avoid, right down to blind obedience.
The former Soviet Union and the current Chinese Communists are good examples of essentially making their own state worship / obedient humanist worship religion to try to supplant other religions so they didn't go into full on law of the jungle. And just like most religions they also eventually have a period of brutally suppressing any competing religions and eliminating the heretics.
However don't wax all romantic for Roman society!
It was horrific by today's standards but that is because people today in the west have the benefit of morals and society that the Christian religion shaped for over a thousand years. Even that changed much over time as the religion evolved, so did accepted morals & society. Modern Christians today, even most of the "devout" ones would probably not fare well in times 500 to 1000 years ago as the times / morals / society / religion was a lot more brutal/bad/horrific than most understand.
The same religious forces are at work today as the woke left wing SJW crowd is making a religion of their fringe beliefs that they are trying to force on everyone and science be damned, the truth is heresy and you will only think what they tell you to think or you are a heretic and must be destroyed, even if what you are saying is actual physical fact and easily proven science.