To my perception, only absolute cults and specific sects of evangelical, monotheistic religions seem to require this degree of exclusivity within their belief structures. It suggests an insularity born of defensiveness -- but truly following the strict teachings requires nothing less.
To what extent does a societally sanctioned religious structure of this sort shape its symbiote society? or is its very structure a direct result of a particular societal structure or composition? If so: what are the key elements of such a society?