But is it Grinch-like to say "there's no afterlife" to Christians? No, but beating one's speculative opinions over anyone's head while asserting it's "the truth" when you can't demonstrate it's true, is just preaching.
Does behavior associated with non-scientific thinking after a certain age constitute a mental illness? If not a mental illness at least a mental deficiency? We should want to understand the mechanism behind a 55 year old person claiming to believe in an afterife because they want to be with their mother again. We should be able to know how that happens in one person and not another just as easily as we can know how it happens that one person can be 6'10" tall and the next person 5'2" tall. After all, both are simply differences in expressed behaviors. It isn't magic so why do we struggle for answers?
I find this article quite informative when it comes to discussing this aspect of human behavior.
We do know the answer to this question, though, pretty clearly. In evolutionary terms being swayed by one's culture is a feature, not a bug. When people are firm believers in the culture they're raised in, belief happens, children happen. When people are smart enough to know that it's all meaningless and religion is untrue, children tend not to happen.
Wishing this wasn't so doesn't make it not so.
That's right.
What makes it not so, is that
it isn't so.
Evolution doesn't work in quite such simplistic ways, and it operates on populations, not on individuals.
In evolutionary terms, it's optimal for reproductive success
in the very long term for social animals to
mostly be compliant with the rest of their circle, with only a few radicals, revolutionaries and mavericks who won't simply follow a leader, but who will instead aspire to leadership themselves.
Leaders don't go extinct, even though the optimum individual strategy is to be a follower. That's because if every individual follows that strategy, the entire community collapses for lack of leadership.
How that broad evolutionary trend over large numbers of generations applies in the specific case of
Homo Sapiens, with its vastly complex and highly volatile belief and social structures, is quite simple - it simply doesn't.
Genetic factors that are not conducive to the production of offspring do NOT go extinct, if they are not expressed phenotypically in a significant subset of those who have the geneotype in question, and are beneficial at the population level when expressed.
This is why "Idiocracy" isn't a documentary; It's also why homosexuality hasn't gone extinct, and nor has monasticism. It's why scientific racism is just racism; And why eugenics is stupid and futile, as well as being immoral.
Evolution is a biological phenomenon. Worse, it is a population level biological phenomenon. Which means that Bilby's Law of biological explanations applies in spades: Any description of how a biological system operates can always be improved by the addition of the phrase "...but, of course, the reality is far more complicated than that".
Culture is subject to evolution, just as all of biology is.
But human culture is far too small a subset of human behaviour, and is far too recent, and has far too many non-genetic influences on reproductive success, and is exhibited by a species with very low numbers of offspring per mating, for those evolutionary influences to be detectable.
Come back in another few million years, and tell me about how the cause of widespread religious belief, is that it has been selected by its effect on reproductive success, and I might be persuaded. But with only a few million years of
Homo, and only a few hundred thousand years of
Sapiens, confidently ascribing modern human behavioural traits, much less specific ways of thinking, to evolution alone, is a serious stretch.