The danger of religion. .

[Polaris]

Atheists killed the most! No, Christians killed the most! What about them Muslims! And those fucking pagans! Oh, look; we're almost at the centre of the Earth - keep digging!

Actually, strictly speaking without adding any meaning to the word beyond what it actually means, atheists have killed and continue to kill the most people depending on the year (sometimes religious conflict* is responsible for more deaths in a certain year, sometimes secular strife in another year).

*The US and foreign intervention is responsible for the majority of the high-casualty religious wars though. Sure the Middle East was already a powder-keg full with pent-up tension and frustration, but the US is partially responsible (the USSR was the other instigator) for igniting the fuse.