Critics never tire of blaming religion for the world’s divisiveness, hatred and wars. They point to such things as the many Protestant/Catholic conflicts, the Crusades, and (in modern times) the Hindu/Muslim clashes that produced separate states of India and Pakistan. More current examples include Sunnis and Shiites; Jihadist Islam; the Buddhist persecution of Muslim Rohingyas in Myanmar, and the ultra-Orthodox minority in Israel that threatens Muslims and liberal Jews alike.
These are indeed instances of people using religion for evil, just as critics charge. But saying that something is often used for evil ends does not imply that the thing being used is evil in itself; or that in different hands, it cannot equally be used for good. Food, for example, causes obesity; but no one concludes that all food is bad. Logic can lead to error, but we do not conclude that we should aim at being illogical. It is specifically bad food (or food badly used) and bad logic (or logic wrongly applied) that bring us grief. The question with everything is how it is used and why people use it that way.
Actually, it is not so much religion that has been at stake as it is religious ethnicity, because for most of human history (and even today) religious belief has been inextricably tied to the stuff of ethnicity. Ought we, then, to get rid of Klezmer music and Pakistani food?
The truly monumental evil of our time comes from neither religion nor ethnicity, however. It is nationalism wed to ideology that gave us the Great War of 1914; nationalism wed to racism that gave us Hitler; and totalitarian ideology that produced Stalin.
We should differentiate cause from reason. Cause is the set of circumstances that produce a phenomenon; reason is the stated justification for that phenomenon. Religion, ethnicity, nationalism, and ideology are just some of the reasons cited by those who wage the wars or inflict the cruelties in question. People bent on these evils select any reason that seems in vogue. Religion has been one of them, but if religion had not been available, the perpetrators would have chosen something else.
The culprit is not religion, but religion misused; and religion misused is just the reason , not the cause. Religion alone causes nothing.
Nowadays, when critics cite religion negatively, they usually mean the religion practiced by people who dislike modernity and who want to turn back the clock to some imagined halcyon yesteryear. Such people do not use religion alone as their rationale, however. They are equally likely to champion ethnicity or nationalism, the way the nineteenth century tended to prefer reasons of race. Any one of these can be misused to rationalize evil. None of them actually causes it. The cause is fear of modernity, to which gets added any reason whatever that will make deep-seated fear seem legitimate.
Distrust of modernity is just the proximate cause, however. The deeper cause is change itself, particularly because change carries with it a redistribution of power. In our time, the cutting edge of change, worldwide, is likely to feature acceptance of science; religious reform; international collaboration; advanced education; the obliteration of old ethnic prejudices; a global economy; and the like. The opposition champions the reverse: suspicion of science, a return to old-time religious verities, nationalist pride, localist loyalties, and ethnic solidarity.
Overall, religion has more often been a blessing than a curse. It comforts the suffering, achieves community with purpose, insists on ethics, and posits a better world worth having. It challenges us to reach higher, act better, and believe more fully in the best that humanity has to offer. Throwing out religion because we abhor how some people use it is like throwing out the baby with the bath water. We would be better off demonstrating the many ways that religion enriches human lives, and letting the baby work its many positive miracles upon us.