An established church is a church given special recognition by a national government. The church represents the official religious faith of the nation and receives support from the government, in a wide variety of forms from financial assistance to legal protections. Established churches can be seen in many regions of the world, although some nations, like the United States, have laws specifically prohibiting the creation of an established church, in the interests of maintaining a separation between church and state.

Christian, Buddhist, and Muslim sects can all be seen in roles as established churches in nations like England, Bhutan, and Saudi Arabia. In nations with an established church, the head of government may also be the head of the church, and people may be required to follow the teachings of the church, although this is not always the case. In some regions, while the church enjoys official government recognition, many citizens are not among the faithful and do not attend church.

Some nations have adopted an existing religion as their established church, while others have established their own denominations. In cases where the state creates a church, the established church cannot make changes in policy without consulting the state, and the state cannot change the laws pertaining to the church without discussing the matter with religious leaders. The Church of England is an example of a state church of this nature.

Acceptance of other faiths in nations with an established church varies. Some countries promote freedom of religious expression, allowing their citizens to practice any religions, or none at all, if that is their preference. They may also actively protect the right to worship any faith peacefully through laws and other measures. In other regions, religions or sects seen in conflict with the established church may be suppressed and people who belong to those groups may be persecuted. Historically, nations were sometimes quite brutal about their enforcement of religious faith, as seen during the Inquisition in Europe.

Some nations that once had established churches have chosen to abandon the established church in the interests of protecting the clear divisions between church and state. In these countries, people are welcome to continue practicing the faith, but it is not longer recognized as the official church of the government. Nations have also changed allegiance, as seen in England when King Henry VIII broke with Roman Catholicism and established the Church of England.