Interesting article. Note that it only talks about improving cooperation "within" the circle, i.e. among "co-religionists", as the article puts it.

I think you'd find increased cooperation within many other types of groups. What we should aim for, of course, is to expand this circle of concern ever further, beyond religion.

So, just want to clarify that this might have been an benefit of religion in earlier days, but is by no means an argument for them today.