I've heard several comments about the power of religion to prolong life expectancy, even on science programs (last night on the TV for instance).
I can believe that prayer can provide some sort of outlet for your frustrations and calm you down, but religion? No, I don't think so.
It's true that congregations tend to be made up of more older people than the average, but I would expect that if they are so looking forward to the life hereafter, then why should they care so much about staying on earth?
I know a priest in his 90's, but I also know people of a similar age who have never gone to church in their lives.
And does religion here mean any old nut-cult or does it mean the mainstream faith?
For some reason this reminds me of Samuel Butler's novel Erewhon Revisited. The hero of the novel escapes from a land called Erewhon (Nowhere) by balloon. Some time later he returns to find he is worshiped as The Sunchild by the Church of Sunchildren, who believe that he ascended into heaven. Butler doesn't study the effect on life expectancy, but I'm sure that the population were much the same lived. On an island in the Pacific (Vanuatu) the John Frum cargo cult believe that a WW2 serviceman will return one year on February 15th. The leader of the cult stated only in 2007 that John Frum was their god and he would return. Maybe it's belief, no matter what, that might have an effect on life.
Now clearly both the Sunchildren and the cargo cult have just a valid reason to be called religions as any other, because from their point of view they have identified with the supernatural. So I think that any statement about religion prolonging life must be qualified by a definition about what religion really is, and that is a belief in the supernatural, and has nothing whatsoever to do with the truth of any single faith system.
Life expectancy in a deeply religious and rich country like Saudi Arabia is 72. In the United Kingdom, which does not thrive on religion, it is 80. So I think that alone proves a point.