European demographers rarely study religion as a determinant of contemporary demographic behaviour. One reason could be the secularisation observed in European countries, implying that the effect of religiosity has been diminishing. This paper aims to show that religion can have an important impact on ideals, intentions and behaviour related to fertility.First we discuss recent trends in religiosity. We base our ensuing hypotheses on three deliberations why religion may have a bearing on fertility: importance of religious teaching, effect of social capital and function of religion to decrease uncertainty.Using FFS data we examine the influence of several measures of religiosity on the ideal number of children and intentions to have a second and third child, as well as on the expected and actual number of children. We find that all measures of religiosity are in general related to a higher ideal number of children, higher odds to intend another child and higher expected and actual number of children. Participation in religious services turns out to be slightly more salient than affiliation and self-assessed religiosity. We also discover that the effect of religion on ideals is more pronounced than its effect on intentions. Ideals stay further away from behaviour than intentions do and hence the influence of religion is intermediated by other social systems.