Sue Blackmore was a champion of the idea that religions are “memeplexes” that act purely in their own self-interest, to the detriment of the population whose minds they infect. She wrote a couple of books on the topic, to explore the extend in which this theory could be true.
I recently stumbled on an article she wrote in 2010, published in The Guardian: Why I no longer believe religion is a virus of the mind. In it, she mentions all the benefits religions have for humans – it is “biologically adaptive”, in the sense that it actually benefits the genes too: religion may lead to happier, healthier lives, but most importantly (from a biologically adaptive perspective), religious people have far more children than non-religious people.
She points out that the meme and memeplex perspective is still useful, the memeplex just cannot be considered a “virus” by any sane definition of the word:
Religions still provide a superb example of memeplexes at work, with different religions using their horrible threats, promises and tricks to out-compete other religions, and popular versions of religions outperforming the more subtle teachings of the mystical traditions. But unless we twist the concept of a “virus” to include something helpful and adaptive to its host as well as something harmful, it simply does not apply.
So, again: we can still study the memes (the ideas that are passed on from person to person) that are present in religions, and how they help the “memeplex” (the collection of memes that together compose these worldviews), but failing to recognise how they also benefit the religious peoples on a biological level, is failing to see a big part of the picture.