Anti-clericalism is a historical movement that opposes the clergy for reasons including their actual or alleged power and influence in all aspects of public and political life and their involvement in the everyday life of the citizen, their privileges, or their enforcement of orthodoxy. Not all anti-clericals are irreligious or anti-religious, some anti-clericals have been religious and have opposed clergy on the basis of institutional issues and/or disagreements in religious interpretation, such as during the Protestant Reformation.

Anti-clericalism in one form or another has existed through most of Christian history. Some philosophers of the Enlightenment, including Voltaire, attacked the Catholic Church, its leadership and priests claiming moral corruption of many of its clergy.

The French Revolution, particularly in its Jacobin period, initiated one of the most violent episodes of anti-clericalism in pre-modern Europe; the new revolutionary authorities suppressed the church; destroyed, desecrated and expropriated monasteries; exiled 30,000 priests and killed hundreds more. As part of a campaign to de-Christianize France in October 1793 the Christian calendar was outlawed, replaced with one reckoning from the date of the Revolution, and then an atheist Cult of Reason was inaugurated, all churches not devoted to that cult being closed. In 1794, the atheistic cult was replaced with a deistic Cult of the Supreme Being. When anticlericalism became a clear goal of French revolutionaries, counter-revolutionaries seeking to restore tradition and the Ancien Regime took up arms, particularly in the War in the Vendée (1793 to 1796).