This paper surveys the field that has come to be known as the epidemiology of religion. Epidemiologic study of the impact of religious involvement, broadly defined, has become increasingly popular in recent years, although the existence, meaning and implications of an apparently salutary religious effect on health have not yet been interpreted in an epidemiologic context. This paper attempts to remedy this situation by putting the "epidemiology" into the epidemiology of religion through discussion of existing empirical findings in terms of several substantive epidemiologic concepts. After first providing an overview of key research findings and prior reviews of this field, the summary finding of a protective religious effect on morbidity is examined in terms of three important epidemiologic concepts: the natural history of disease, salutogenesis and host resistance. In addition to describing a theoretical basis for interpreting a religion-health association, this paper provides an enumeration of common misinterpretations of epidemiologic findings for religious involvement, as well as an outline of hypothesized pathways, mediating factors, and salutogenic mechanisms for respective religious dimensions. It is hoped that these reflections will serve both to elevate the status of religion as a construct worthy of social-epidemiologic research and to reinvigorate the field of social epidemiology.