It's a bit of a false dichotomy, there's a broad spectrum in both.

A lot of the benefit of religion doesn't come from the beliefs itself, but the community around them. You could just have a community built around other things, or even a religion that doesn't mandate theism (UU's and Quakers come to mind, they have fairly large atheist populations. There's also less "serious" religions, like TST).

I doubt there's much correlation either way

Living under Christianity means living in constant fear of being watched and judged and living in a world full of supernatural forces. It was a great relief when I realized it's all bullshit.

oh wow, a wrong question

Depends on the person. If you're happy living in wonderland, theism is the way to go

It can play a role but there are so many other factors. Some people turn to theism to cope with hardships which means they are less unhappy thanks to it. But on the other hand there are people who live a restricted frustrating childhood in a religious family and finally experience freedom with atheism.

It's more interesting to ask ourselves what precisely religion brings to the table, the negative and the positive, so we can answer difficult political questions in relation to religions