The spread of religions and quasi religions over the last two millennia has been part of the process by which groups and societies have been required to define themselves in response to outside pressures. Acceptance, rejection, or mixed acceptance of religions introduced from the outside are highly dependent on intersocietal relations in which receiving societies perceive themselves to be threatened by the society from which the religion comes or by other societies. Religions have been important resources for societal definitions that help to maintain societies in opposition to threat or in uncertain conditions. Religions from unthreatening societies have aided threatened or unstable societies to assert their distinctive identities, but religions from threatening societies have been resisted in various ways. A historical review of the spread of three major world religions supports this theoretical perspective.
