A new article in The Atlantic draws attention to research by the Pew Global Attitudes Project in 2007. This research shows a strong negative correlation between GDP per head and religiosity, ie the most religious countries are the poorest. (Except for the USA and Kuwait!)
The author argues that increasing income reduces religious commitment - and even quotes John Wesley in support! That's very plausible. But it's also likely that religiosity depresses income through its hostility to this world and resistance to innovation and critical thought. Indeed, both may be true - a positive feedback loop.
To test this we'd need to track wealth and religiosity over several decades. I wonder if anyone has done so.
9 hours ago in The Phytophactor