alt Hacker NewsI doubt it's quite that simple, but this does seem likely to be a big factor. I say this as an atheist myself. Religion does seem to give people a purpose and a community that's difficult to find elsewhere, and that translates to happiness. Sometimes I wish I could do it, but I can't.
While a fall in religiosity may be part of the cause, I don't think a return to religion is the answer. We need to find ways to replicate the non-supernatural aspects of religion without the weird stuff.
I think this is a common reaction that I used to agree with but no longer. I think religion tends to capture something essential about reality that atheism excluded by definition.
There's a reason no atheist society has historically arisen and thrived in the way that you are suggesting. If it was possible why hasn't it happened. The idea of atheism is ancient - why has it not worked?