Can I be late to the party on this? I haven't read this thread. Apologies to Josh.
As anyone who knows me knows, I am an atheist. But...I believe religion is generally a good thing.
A huge critique about religion is that it divides us by making our brother man seem different, and different is easy to see as less equal, and then the enemy, and then finally inhuman. But in some hypothetical land where there weren't religion, there would be something else. In fact, there are already plenty of "something elses". There's nationalism, there's culture, there's ethnicity, there's income, there's profession, there's skin color, and there's gender, to name a few.
Those are all things that can divide - that do divide - but they also unify, because they are all commonalities. Religion acts as a commonality as well. And unlike all those other things that divide, most religions do promote something greater than themselves: charity, and when done right, love for fellow man. And if nothing else, purpose and hope, even if it is a falsity. Do non-religious groups do this as well? Of course, but not on the same scale, and that is a relatively modern invention anyway.
Now, it is easy to find religious people who hate, who ridicule, who even kill those others who are not like them. But as I said, it's easy to find that in every human group, because the behavior is common to all mankind. And don't tell me, "Well, religion is the cause of most of it." No, religion is the excuse of most of it. Do you think the British Empire really wanted to "convert the savages" when they invaded various countries? No, they wanted land and resources. Do you think the Muslim conquests of Jerusalem and the Catholic's church crusade against them was really about religious differences? No, it was about who held a seat of profound social, political and financial power. Do you think religion had anything to do with witch hunts and the Inquisition? No, it was a way for various church groups to remove political rivals while also securing a power base. Do you think the countless issues with female genital mutilation in Africa and the Middle East have anything to do with Islam? No, it is a cultural practice that spans back well before Islam's founding. These conflicts and more would have happened in some fashion at some time, even without religion.
You might be thinking now that, religion is still bad because it is used as an excuse, and it is used as a means to control people. Yes, that is true. But let's look at some non-religious examples, hmm? McCarthyism is a great recent example. Yes, there is a tidbit about godless communists, but the driving force was really capitalist vs communism, not religion. It was used as an excuse for a great many civil liberty violations. And what about the persecution/internment of German and Japanese American citizens during WW2? Despite many of the families being in the country for decades...well, you are THIS ethnicity, so off to camp you go! And there are a great many racial hate crimes committed all over the world, by groups (and individuals). Are you black in the South in the wrong decade? That's a beating, despite often being the same religion. And that shit still goes on in South America to some extent. Women in Africa and India get gang raped, despite it expressedly being against their religious teachings, and the "police" look the other way because it is a "cultural" thing. And just look all over the Middle East to see how people of the same religion (and even the same subsect, Sunni or Shi'ite), will happily kill each other over tribal and racial distinctions (and primarily, who controls land).
So what is the common cause of all this? There are differences between people and eventually they come to blows. But no one thing is truly the root cause of this evil.
Individuals might be motivated by religious beliefs to commit atrocities, but that is rarely the cause of a group action, and it is never the sole cause that group has.
Although I can only imagine what the Aztecs were thinking.
We do not often hear about the good things that people do (in the name of religion or otherwise), because it rarely makes the news or the history books. To me, it doesn't matter why someone does something good for others. I do not care if they think it gets them "points" with God, or if they see it as a social duty, or if they feel simply altruistic. The outcome is the same.
We as a species need to be able to love each other despite our differences if we are ever to truly blossom. If anything, these differences, including beliefs, make us stronger, not weaker. We all come from the same source, whether that is God or not, and we all share the same future.