Realism is capable of serving as a justification for colonialism, supremacy, and genocide even in the absence of apparent religious belief. For example in Australia, some of the cultural genocide against indigenous people took the form of taking Aboriginal kids away from their parents and putting them in white families. There is a Christian justification for this, which is that the kids need to be taught religion. But first off, you can do that by building a church in their community, no kidnapping required. And second, the realist justification, which is that the children must be taught reality, strikes a more fundamental chord in people and appeals even to fake atheists. The idea was that if you taught them maths and English and science in a white school, and European culture and manners and worldview in a white family, you’d “civilise” them. This happened all the way into the 1970s. There’s a lot of people, Christians included, who think that kidnapping a child to teach them Jesus is wrong. But if you instead say you’re going to teach them consensus reality, and use words like “education” and “lifting out of poverty” and “they’re being deprived with their biological parents”, you’ll convince more people that kidnapping is morally right.
And this trend that realism is more complete and more broadly appealing than Christianity or any other religion holds true across many demographics. Realism is a better excuse for bigots to abuse trans people, otherkin, people with schizophrenia, indigenous people, other neurodivergent people, etc. Some Nazis were Christian and some were “atheist”, but all of them were realists.