If religions are born, they must also be able to die. How does this happen? I think we can discount at once the idea that it happens because people realise that science is better.
On the other hand, societies might be reconfigured in such a way that the idea of religion made no sense.
Interestingly, the reverse process seems to have happened in Japan in the 19th century, after American gunboats broke the country’s isolation. According to a recent book from Chicago University Press, there had been until then no concept of ‘religion’ in Japanese society; afterwards, as part of the modernisation, some social practices and beliefs had to be carved out as ‘religious’ while others were classified as ‘non-religious’. The process seems a plausible one, and something like it may be under way in the ‘secularising’ parts of the world today.
This is a process as general and impersonal as language change. Considered in themselves, there is nothing more ‘religious; about a teddy bear left out in the rain by the roadside than there is about a man wearing a white lace-trimmed frock. Yet the teddy bear at the site of a road crash is recognised as a meaningful symbol of our horror at mortality, while the young man in a cotta is no longer a priest linking us to the heart of our civilisation but callow and pretentious.
Perhaps it is easier to think in terms of gods dying, rather than religions. And if we were to classify religions as involving different forms of worship, then you could certainly think that the extinction of worship towards a particular deity would count as the extinction of that religion. Certainly we can be sure that the religion of the Aztecs is dead with their gods, along with thousands of others we can no longer reconstruct.
A slightly less scholarly approach is found in Terry Pratchett’s Small Gods, where there is a desert full of shrivelled starving deities who will vanish altogether if they cannot find someone to believe in them. Pratchett, being a child of English Anglicanism, underestimates the importance of ritual and overestimates belief, but it does seem clear that deities die when no one prays to them. That’s something subtly different to believing in them.
But there is another threat to organised and literate religions: heresy: wrong belief and a misapplication of the sacred. In this context one of the most interesting texts is CS Lewis’ denunciation of female priests. They would, he said, constitute a new religion. Yet, when they came, we can see that they appeared as a simple inevitable, development of the old one. They are still priests. And it is this fact which illustrates better than anything the living and evolutionary nature of religions of all sorts. We can see religions have been born, and have died, but the moments of birth and death will always be mysterious and shrouded.