From a sociological perspective, the identity formation of strong social groups such as those generated by nationalism, ethnicity, or religion, is a causal aspect of practices of persecution. says it is these communities, who can be a majority or a minority, that generate violence. Since the development of identity involves 'what we are not' as much as 'what we are', there are grounds for the fear that tolerance of 'what we are not' can contribute to the erosion of identity. Brian J. Grim and Roger Finke say it is this perception of plurality as dangerous that leads to persecution. Both the state, and any dominant religion, share the concern that to "leave religion unchecked and without adequate controls will result in the uprising of religions that are dangerous to both state and citizenry," and this concern gives both the dominant religion and the state motives for restricting religious activity. Grim and Finke say it is specifically this religious regulation that leads to religious persecution. R.I. Moore says that persecution during the Middle Ages "provides a striking illustration of the classic deviance theory, is based on identity formation, as it was propounded by the father of sociology, Emile Durkheim". Persecution is also, often, part of a larger conflict involving emerging states as well as established states in the process of redefining their national identity.