Well I think it's common knowledge that our brain exerts a certain amount of influence over our body, and therefore the side effects of believing one is about to "burn in hell" or "Sit at the right hand side of the Lord" are quite obvious.
However, when you survey a predominately religious population on their religious beliefs, how can you logically expect objective results? Suppose that survey was conducted in a "fantasyland" that consisted of 90% atheists? Interestingly enough, I think the majority on that one would be significantly higher than 56% but that's another story.
Simply put, the survey fails to address alternate beliefs. I "believe" in man and science and the "miracle" of technology happens with considerably more frequency than those of a religious nature....and I am just as healthy as the next guy,
44% of doctors surveyed say so