Religious discrimination is treating a person or group differently because of the particular beliefs which they hold about a religion. This includes instances when adherents of different religions, denominations or non-religions are treated unequally due to their particular beliefs, either by the law or in institutional settings, such as employment or housing.

Religious discrimination is related to religious persecution, the most extreme forms of which would include instances in which people have been executed for beliefs which have been perceived to be heretical. Laws that only carry light punishments are described as mild forms of religious persecution or religious discrimination. In recent years, the term religionism has also been used, but "religious discrimination" remains the more widely used term.

Even in societies where freedom of religion is a constitutional right, adherents of minority religions sometimes voice their concerns about religious discrimination against them. Insofar as legal policies are concerned, cases that are perceived to be cases of religious discrimination might be the result of interference in the religious sphere by other spheres of the public that are regulated by law.