This is going to sound weird, but hear me out. There are upwards of 4,300 religions in the world, and even faithful churchgoers don't believe in 4,299 of them. My only difference with them is that I don't believe in 4,300.
Is that really such a big deal?
Wikipedia has the European war of religion, including the 30 years war, at 4-12 million deaths (Encyclopedia Britannica has it at a measly 8 million). Not to forget the Crusades, Spanish Inquisition, Suni vs Shite, and of course the Holocaust.
If only those atheists believed in some form of deity.
On reflection, perhaps the different religions can be thought of as a bit like different engineering conventions.
Does current flow from positive to negative or negative to positive? Well, both can work. It's perhaps slightly easier if you pick one and stick with it.
Who is the atheist in this analogy? Dunno. Perhaps the person who asks why we need all these hidebound conventions, and why can't we reason everything out from first principles. Not a bad question to ask. In moderation.