A Secular Look At Religion So, since religion is common amongst humans, it must serve some beneficial purpose, or else people would either quit believing in it, or the believers would die out. — Brendan Golledge
It has propagated through time. There is nothing more to take away and certainly no indication that any evolutionary process (literally or as an analogy) is 'beneficial'.
That aside, there are numerous issues with how you are framing the term 'religious' as a purely Abrahamic monolith. There are plenty of instances of religions that are far far less concerned with deities and some not at all. It is too easy to start in one's own back garden and assume it maps onto everyone else's back garden so easily (if they possess one at all!).
One extremely common feature of religion is that they involve rituals and methods that actively induce altered states of consciousness. This is quite clearly prevalent and universal, with methodologies replicated all over the globe independently of each other.
I have recently started reading Robin Dunbar's
How Religion Evolved: And Why it Endures, I think it would be right up your street.
One major feature of his ideas are attached to the
Dunbar Number, which shows how prior to the occurrence of religious institutions populations of tribes would inevitably reach a maximum before dividing into smaller groups. His premise being that religions have allowed us to create a greater sense of community beyond our natural social capacities.
He does touch on other areas too. Anyway, I would suggest taking a look if you can
:)