Disentangling the Demographic Drivers of Religious Population Change in Northern Ireland

Abstract

This paper sets out to investigate the components of religious population change in Northern Ireland between 2001 and 2011. The results will provide a better understanding of the demographic drivers behind the well-documented decline of the Protestant population and growth of the Catholic population. Previous studies researching Northern Ireland’s changing religious demography have relied on aggregate census data and church records to derive estimates of fertility, mortality and migration differences between religious communities. Data from the Northern Ireland Longitudinal Study now makes it feasible to measure the relative importance of births, deaths, migration and inter-census religious identity change. Findings show that the Catholic population grew predominantly from a surplus of births compared with deaths. For the first time, this paper reveals that a significant proportion of Catholic population growth is attributed to immigration. The decline of the Protestant population was caused by secularisation and emigration, with natural population change playing a reduced role. Now constituting a large minority, the non-religious population grew as a result of all three demographic drivers. Religious conversion and immigration were important factors in the significant population growth of NILS members belonging to Other religions and faiths.