'Does religion cause health?': differing interpretations and diverse meanings.

The question, 'Does religion (or spirituality) cause physical health benefits?' may be given at least four diverging interpretations in terms of causal path diagrams. In common usage, the question may be interpreted to indicate that religion causally influences health by: (1) any mechanism, including well-established factors such as social support and improved health behaviors; (2) additional mechanisms, such as enhanced positive psychological states (e.g. faith, hope, inner peace) acting through psychoneuroimmunologic or psychoneuroendocrinologic pathways; (3) offering psychological strength for acquiring or maintaining positive health behaviors; or (4) causally influencing health by distant healing or intercessory prayer. We review historical confusion between these interpretations, arguing that disentangling them is important for collaborative health care, promotion and research.