Whether the doctor in a white coat or a priest in a dark robe - faith can heal and it can kill (witness Vodun, voodoo). Belief matters. When I was six I had several warts on my hands. My old granma performed a ritual involving rubbing them with a bean which was then buried beneath the eaves of her house with a small wooden stake holding it down. Done in a very solemn manner by someone I believed in, the warts were gone in 48 hours. Mumbo jumbo? It worked.

Obviously, not everything can be handled this way any more than everything can be handled with modern medicine. But every disease has a component that can respond to faith, both positively and negatively.