Yeah okay mate that's one example of an "atheist" killing some people.
What about literally every other war out of any time period?
Reminder it was good-hearted Christians that nuked civilians.
So many times it's just religious zealots and their "GOD WILLS IT" bullshit that motivates armies.
Stalin killed a lot more innocent people than the crusaders and hiroshima and nagasaki did.
A LOT MORE Especially considering the Crusades were literally a reactionary movement because of muslim attacks in Iberia.
Regardless, War is a human folly, not a religious one. Religion isn't some all-powerful force for good for me, but humanity would war without it. Wars are declared with religion as a factor, but there are plenty more wars declared purely with political and monetary gain, spite, and revanchism as causes.