Freedom of religion is a principle that supports the freedom of an individual or community, in public or private, to manifest religion or belief in teaching, practice, worship, and observance; the concept is generally recognized also to include the freedom to change religion or not to follow any religion. The freedom to leave or discontinue membership in a religion or religious group —in religious terms called "apostasy" —is also a fundamental part of religious freedom, covered by Article 18 of the Universal Declaration of Human Rights.

Freedom of religion is considered by many people and nations to be a fundamental human right.

In a country with a state religion, freedom of religion is generally considered to mean that the government permits religious practices of other sects besides the state religion, and does not persecute believers in other faiths.

Historically freedom of religion has been used to refer to the tolerance of different theological systems of belief, while freedom of worship has been defined as freedom of individual action. Each of these have existed to varying degrees. While many countries have accepted some form of religious freedom, this has also often been limited in practice through punitive taxation, repressive social legislation, and political disenfranchisement. Compare examples of individual freedom in Italy or the Muslim tradition of dhimmis, literally "protected individuals" professing an officially tolerated non-Muslim religion.