Exorcism belongs to Christianity's oldest self-description: the Gospels present the casting out of unclean spirits as a signature of Jesus's ministry, and the early church institutionalised the power with striking speed. By the mid-third century Rome had a formal order of exorcists, one of the minor orders through which clergy passed for seventeen centuries, and catechumens preparing for baptism underwent repeated exorcisms as a matter of course. The medieval church multiplied formulas of very mixed quality, and it was to discipline that abundance that the Rituale Romanum of 1614, part of the Tridentine standardisation of the liturgy, published one authorised rite with rules for its use, a text that then served essentially unchanged into the twentieth century. The Second Vatican Council's reform reached exorcism last of all the liturgy: the revised rite De Exorcismis et Supplicationibus Quibusdam appeared only in 1999, strengthening the requirements of episcopal permission and prior medical judgment and softening some imperative formulas, to the public disappointment of some veteran exorcists who found the old commands stronger; the older text remains usable by permission.
The rite's recent history is a paradox: as Western dioceses grew cautious, demand rose, driven by film, by charismatic deliverance ministries outside Catholic discipline, and by global south Christianity's lively demonology, and the church has responded institutionally, with training courses in Rome and an international association of exorcists recognised in 2014, seeking to keep an ancient rite inside its own guardrails.