Flagellants are practitioners of a form of mortification of the flesh by whipping their skin with various instruments of penance. Many Christian confraternities of penitents have flagellants, who beat themselves, both in the privacy of their dwellings and in public processions, in order to repent of sins and share in the Passion of Jesus.
In the 14th century, a movement within Western Christianity known as Flagellantism became popular and adherents "began beating their flesh in a public penitential ritual in response to war, famine, plague and fear engendered by millenarianism." Though this movement withered away, the practices of public repentance and promoting peace were adopted by the flagellants in Christian, especially Roman Catholic, confraternities of penitents that exist to the present-day.
Flagellation (from Latin flagellare, to whip) was quite a common practice amongst the more fervently religious throughout antiquity.
Christianity has formed a permanent tradition surrounding the doctrine of mortification of the flesh, ranging from self-denial, wearing hairshirts and chains, fasting and self-flagellation using the discipline. Those who practice self-flagellation claim that St. Paul’s statement in the Bible ‘I chastise my body’ refers to self-inflicted bodily scourging (). There are prominent Christians who have practiced self-flagellation. Martin Luther, the Protestant Reformer, self-flagellated among other ascetic practices during his early years as an Augustinian friar (although he later condemned such practices). Likewise, the Congregationalist writer Sarah Osborn also practiced self-flagellation in order "to remind her of her continued sin, depravity, and vileness in the eyes of God". It became "quite common" for members of the Tractarian movement within the Anglican Communion to practice self-flagellation using a discipline.