The science of DNA genetics is getting very popular. Of course, DNA goes much, much further back in time than religions of today do.

People are very similar, genetically. Why is there so much animosity?

What probably happened, 8 or more thousand years ago, was the sacred mushroom supplies dwindled, due to cold periods and ice ages. What little supplies remained had to be protected, so military groups and countries were formed.

Eventually, humans replaced the sacred mushrooms with booze, and/or superstitious, exploitative bad religions. Things have been going downhill ever since. Bad diets do not help, either.