That's because the more rational amongst us have stopped putting up with people killing other people on purely religious grounds.

Is apostasy still a crime punishable by death? It used to be. So was homosexuality. Thousands of innocent women were tortured and some even burned at the stake for so-called religious "crimes".

People were still killing each other for reasons they'd consider "rational" back then too... but getting rid of any reason for irrational killing is, I think, a step in the right direction - one brought about by rational, enlightenment thinking.

When we can get rid of the rationalised, non-religious reasons too, then we'll really be onto something good.