The problem with any theory of why people are religious is it can't differentiate between the true-believers and those who see it as an opportunity for networking, selling and whatever.
The split between those groups may be down to education which could explain why there isn't a difference in religiousity (a word?) that can be seen - they are there for different reasons.
But the way obviously intelligent people and often sceptical people who question other things, can still be believers never ceases to astonish me.