There are two reasons I doubt this:

(a) is such a belief really compatible with what we think is the selective force of evolution, i.e. stay alive long enough to make sure your children have children? In other words, is this something people truly feel when it comes down to it, or is it just a story they tell each other in low-stakes situations? and

(b) even if I believed in this, that's orthogonal to my belief that every human has a valuable role to play in this, current-life society!

Evolution doesn't suggest everyone reproduces or "stays around long enough to make sure your children have children" . In World War 2 for example lots of 18 year old men for example were drafted and sacrificed their lives without having a chance to reproduce. Taking your thought experiment to it's conclusion you might conclude world War 2 couldn't have happened.

Your argument about selective pressure would by the same logic lead one to conclude chaste nuns can't exist and monestaries and vows of celebacy are fiction.

Religious belief just needs to be useful on average for there to be selective pressure.

Also evolutionary psychologists can't really explain the existence of gay people (attempts to do so have been a stretch, according to the evolutionary psychiatrist author of The Moral Animal) which demonstrates the limits of declaring things are impossible due to thought experiments about evolutionary pressure.

>i.e. stay alive long enough to make sure your children have children? In other words, is this something people truly feel when it comes down to it

The Aztecs sacrificed an estimated tens of thousands of people a year, because they believed it would postpone the next apocalypse in which everyone would die

But do we think this was a belief shared by everyone until their deaths, even the people who were sacrificed? Or was it a belief primarily instituted by people who thought they, themselves, would never be sacrificed?