What is the function of religion?

[Faith No More]

But what if there are aspects of reality that religion makes it easier to accept as real?

And one can live in delusions without religion.

But don't misunderstood: I am not particularly fond of religion ...

If you want to convince me that religion is worth keeping, you'll need more than "what if's."

On the basis that non-religious societies have been the losers in the game of survival of the fittest between societies.

That's the hypothesis.

Your claim was that all societies have been religious, so you have no way of observing that.