This thesis develops and tests a social network theory of religion to explain the phenomena of religious and secular beliefs in the general population in contemporary Britain. Drawing upon the writings of several historians and upon the work of Giddens (1994a, 1994b), the study is placed in the theoretical context of the debate about the nature of modernity. Due to the various processes of modernization it is argued that personal network links between church attenders and non-church attenders have gradually been severed since pre-modern times. The immediate consequences of this development are twofold. First, the transmission of church religion is greatly restricted. Second, personal overarching religious, or indeed secular, world views are now likely to be formulated, maintained, modified and transmitted by individuals within discrete and geographically dispersed social networks within the private sphere. On the basis of this argument a network dependency hypothesis was formulated, from which twenty-two testable propositions were derived. By employing ego-centred network analysis, the empirical dimension of this thesis reports the testing of each of these propositions against data obtained from a quantitative 500 questionnaire survey of a middle class suburb in the south of England, followed by 39 qualitative focused interviews with informants selected from the initial survey. The data showed that responses to the process of primary socialization had a profound effect on the initial belief formation of ego. This provided a foundation both for religious or secular belief in later life and for the future selection of network alters. With the exception of conversionists, these beliefs generally continued to be maintained by ego within ego's current network. At all stages ego demonstrated a need to reduce cognitive dissonance and to pursue cognitive consonance (Festinger, 1985). The local community did not constitute a plausibility structure and even the local church did not perform this function. Only discrete, dispersed, personal networks in the private sphere functioned to maintain the plausibility of religious and secular beliefs. The findings constituted overwhelming support for the network dependency hypothesis.