I'm curious what your evidence is for this. It seems plausible but when you look at the most atheist countries, its a grab bag of prosperous western countries and not so prosperous former communist countries.
It's very difficult to come up with bulletproof evidence for this - the scope of scientific
experiments is limited - but ...
1) The prosperous Western countries that you mention.
2) The former communist countries that you mention. They may not be as prosperous as the western countries we usually refer to, but the ones that remain irreligious tend to better off than the ones who don't.
3) Cuba, for instance, was seized by religion of the Afro-Cuban variety when the Special Period began.
4) Psychological experiments. If you make people insecure, they are more likely to be superstitious.
5) Professions where people tend towards superstition: They aren't usually the ones where people have both secure (!) and well-paying jobs. They are usually jobs with a high level of insecurity: professional sports, stockbrokers, performers, for instance.
6) Individual cases like the children in Beslan. Or the 'atheists in foxholes'. That there are
no atheists
at all is an obvious exaggeration, but the tendency that it describes isn't wrong.
7) The reasons why people believe: 'It makes me happy.' 'Have you heard the good news? 'I've never heard Christians tell me that the reason why they believe in God is that they sat down and seriously deduced that God must exist and they believe in him for this reason. I think you can find people like that online, but probably only when they are trying to legitimize religion to skeptics.
(When I was a child, we used to sing this song In my local Baptist church:
"I am happy, I am happy, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday. I am happy, I am happy, 'cause Jesus is my best friend")
8) Education is always mentioned as the reason why people stop believing in weird things, but even educated people seem to be just as much in denial about reality as uneducated people when confronted with death.
My collection of links:
http://www.internationalskeptics.com/forums/showthread.php?postid=9447804#post9447804