Atheists can't out-breed religionists.

Some stats porn:

Interesting, its not surprising really, we dont breed as much as the religionists do, most atheists I know stopped at one child, if they bother at all.

Fun to analyse it though.

Hmmm, troubling to think that the processes of nature could be selecting against rationality. How nihilistic is that?

Well considering we have made it this far as a species, and “Rationality” is rather new concept as a thing.
Something seems to work maybe the power of religion to organize society had it’s benefits.