Nick Spencer, Director of Studies at Theos, wrote an overview of religion in the 2000s for The Guardian’s Comment is Free: Belief forum on 30 December:
Religion did not roll over and die, as many expected. Rather it migrated from being a fundamentally socio-economic phenomenon, which would simply dissolve when humanity finally arrived at perfect socio-economic conditions, to being a biological one, as hardwired into us as sex or aggression. Almost irrespective of whether religious beliefs are true or false, religious identity, behaviour, and communities are here to stay…
It’s largely concerned with accommodation of religious diversity, including atheism. Not so much on the numbers, but it’s a very interesting read.
