This paper provides a method - and theory - focused assessment of religious behavior based on cross-cultural research that provides an empirically derived model as a basis for making inferences about ritual practices in the past through an ethnological analogy. A review of previous research provides an etic typology of religious practitioners and identifies their characteristics, selection-function features, the societal configurations of practitioners, and the social complexity features of the societies where they are found. New analyses reported here identify social predictors of the individual practitioner types in their relationships to subsistence and sociopolitical conditions (foraging, intensive agriculture, political integration, warfare, and community integration). These relations reveal the factors contributing to social evolution through roles of religious organization in the operation of cultural institutions. The discussion expands on the previous findings identifying fundamental forms of religious life in the relations of the selection processes for religious practitioner positions to their principal professional functions. These relationships reveal three biogenetic structures of religious life involving (1) alterations of consciousness used in healing rituals, manifested in a cultural universal of shamanistic healers; (2) kin inheritance of leadership roles providing a hierarchical political organization of agricultural societies, manifested in priests who carry out collective rituals for agricultural abundance and propitiation of common deities; and (3) attribution of evil activities, manifested in witches who are persecuted and killed in subordinated groups of societies with political hierarchies and warfare. These systematic cross-cultural patterns of types of ritualists and their activities provide a basis for inferring biogenetic bases of religion and models for interpreting the activities, organization, and beliefs regarding religious activities of past societies. Cases are analyzed to illustrate the utility of the models presented.