*Disclaimer: I do not identify as religious, but I am very spiritual. I belong to no organized religious group, and prefer to choose my teachers based on their teachings rather than on their sect. I live in a culture that identifies predominantly as white, western and Judeo/Christian. I also write this stuff primarily to organize my thoughts and make them easily accessible, not to advise others on how to relate to the ineffable.*
Religion does not cause violence. So many folks believe this to be the case, make art and write songs about how getting rid of religion would make a peaceful world. Sorry.
We create religions as a means of sorting "us" from "them". Because as trooping primates, that is what we do. Identifying who we fuck versus who we fight.
National borders are there to mark where our troop has staked a claim on the local resources. If those resources start to get low, we go to war with someone who has more of the resources we need. It is more obvious when we were fighting with rocks and clubs - but it is still what we are doing. We create political constructs to explain why our region of resources is vastly superior to the other guy's. And it makes a handy excuse when we need to go "liberate" his resources for the use of our own.
We will use religion, or political systems, or historic grudges, or assumed territorial violations to rationalize war against the "other". But ultimately it is always just some variation on a resource grab.
Even the seemingly stateless terrorists we see today are quick to declare a "state" and to start attempting to move into and take over regions to acquire their resources. They recruit women to populate those regions with their offspring. Same old story whether it is chimps, Visigoths, or Exxon.
We have evolved socially and culturally quite rapidly, and now with technology our culture is evolving even faster. Our bodies and brains are on a MUCH longer timeline. So no small number of our impulses, coping mechanisms, instincts, etc were developed in a vastly different environment.
And our drive to name, to categorize, to sort is a product of this need to identify what constitutes a threat versus what is "us".
Survival as a species is going to require us to understand and accept this, and to utilize that knowledge using the beautiful large frontal lobes we now possess to guide us going forward. Maybe there are just too many of us and we are not ready for a monkeysphere that encompasses the entire planet. It could be that we will wind up decimating our populations via war-related disease and famine back down to a size that has enough space to keep the current model.