This chapter considers the ways in which freedom of religion might impose demands on not-for-profit law in the United Kingdom. The chapter tackles this question with reference to European jurisprudence, but also the charity law and other common law of the UK itself. The chapter argues that the legal definition of ‘religion’ in not-for-profit law should be as broad as possible, to ensure that freedom of religion is properly respected and that the question of what counts as a religion is kept separate from the question whether a religion should be constrained or interfered with by the state. It further argues that European jurisprudence should be developed with an eye to ascertaining when states might legitimately discriminate between religions, within the ‘margin of appreciation’ that they enjoy under European law. Finally, the chapter suggests that freedom of religion demands the restoration of a ‘presumption’ of public benefit in English charity law or the abolition of the public benefit requirement altogether.