There is no universal definition of religion under English law. Instead, different definitions have been developed by courts and tribunals in relation to different religious rights. Although there have been moves towards the harmonisation of these different definitions, recent decisions have reversed this trend. This article explores for the first time how this has led to a confused and contradictory case law. It begins by surveying how religion has been defined in registration law, charity law, human rights law and discrimination law: the moves towards harmonisation and the counter-tendencies in the recent decisions. It places the recent decisions within their broader legal context and points out a number of contradictions and uncertaintie...