Religion didn't kill humanity and is responsible for the biggest wars in history.
There's still time.
> and is responsible for the biggest wars in history.
Not really. WWII, the biggest war in history, wasn't primarily about religion. Neither, at least as a primary factor, were the various Chinese civil wars and wars of succession, the Mongolian campaign of conquest, WW1, the Second Sino-Japanese War, or the Russian Civil War, which together make up at least the next 10 biggest wars.
In the tier below that, there's some wars that at least superficially have religion as a more significant factor, like the various Spanish wars of imperial conquest, but even then, well, "imperial conquest" is its own motivation.
Lots of victims, but they are not called wars. Probably because they are too long and consist of many smaller events that are actually called wars.
Of course the scale of injury is not comparable to what's possible with weapons of mass destruction in 20 century, so I suppose WWII tops the above, but if adjusted for capability... Just imagine
So do a bunch of pre-modern Chinese internal wars that weren't principally religious conflicts.
Heck, the Crusades taken together aren't even the biggest Christian-Muslim medieval conflict (that's the Reconquista).
Didn't the propaganda start with deporting Jews as an excuse? ...
I'd suggest you check out Tom Holland's "Dominion" if you'd like a well-researched and nuanced take on the effect of (Judeo-Christian) religion on Western civilization.