This summary from the article is helpful:
"Why all the benefits of prayer and religion? First, religion and faith provide social support, a consistent element of happiness and good health. Regular churchgoers not only get support from their community, but they also GIVE support to others, and the altruistic activity promotes better health. Second, religion reinforces a belief system. People bond when they hold common opinions and beliefs, even if it's a form of gossiping. Third, religion and spirituality do what a parent or supervisor at work does: give you 10 laws to abide by. And, although you may not like the regulations set upon you and try to break a few, you are glad they exist, because, for the most part, your life runs more smoothly when you follow them. Finally, faith attaches meaning to events. It gives folks hope, the ultimate stress reducer. Hope, doctors say, is about the best thing you can do for your body. It's better than a placebo."
Given these reasons, it makes sense that the benefits are enjoyed broadly by religious folks of all kinds rather than by any one religious group (as we might expect if this were some sort of sign from above of what The True Religion is).