This article examines the relations between religion and politics in Spain in the last 20 years. After a polarised historical past dominated by the religious cleavage, one of the main features of the Spanish democratic transition was precisely the increasing irrelevance of the religious factor. This change was made possible by the combination of the strategies of religious and political elites for avoiding the politicalisation of religious issues when drafting the new constitution and the intensity of the secularisation process that has taken place in Spanish society. Using empirical data from many electoral surveys, the article analyses the evolution of indicators on religiosity and secularisation and discusses the impact of religiosity in different voter groups. The conclusions underline the weakening of the religious cleavage and the diminishing role played by religious issues in the electoral behaviour of Spanish citizens.