I don’t think religion in itself is necessary. I am living in a “Shame Culture.” You are living in a 'Blame Culture." The things that keep us from doing horrible acts are quite different and yet both cultures survive with rules of behavior, manners and morals.
In a ‘shame culture,’ There is a high emphasis on preserving honour and on not being publicly disgraced’ The root of this is founded in Confucianism. (Now here is an Atheistic Belief System.) Similar to Buddhism, Confucianism postulates no specific dieties. It is a system, as atheistic as any, that stresses ‘Social Order.’ A place for everyone and everyone in their place. Instead of the individual, it stresses ‘social roles.’ When everyone does their job in the social order, harmony is achieved and society moves forward.
Just as Christianity is at the core of Western Civilization, Confucianism is at the core of civilizations in the east. Confucianism, Taoism, and Buddhism, all thrived alongside theistic beliefs because they are atheistic at their core and have nothing at all to say about God or gods. Now, with that said, Confucius and the Buddha have both been divinified and worshiped as ‘spirits’ or ‘god-like’ entities by those who distorted the philosophies into religions. (Again I reference the human psyche and its need to engage in magical thinking and create gods where none exist.)
I’ve probably said enough at this point. I’ll just end here.