heresies

Heresy is a belief or doctrine that deviates from the established teachings of a religious community. The term comes from the Greek hairesis, meaning “a choice” or “a faction.” In many traditions orthodoxy is defined by authorities, creeds, or ecumenical councils, and heresy refers to views formally deemed erroneous or dangerous to the faith.

Historically, accusations of heresy have served to preserve doctrinal unity and social order. Definers of orthodoxy issue definitions, condemnations, and sometimes excommunications. The boundary between heterodoxy (dissenting views) and heresy varies across time and between communities, and the consequences of labeling someone a heretic have ranged from debate to exclusion or persecution.

Christian history offers notable examples: Arianism argued that the Son was created and not co-eternal with the Father; Gnosticism offered esoteric knowledge and often a dualistic cosmos; Pelagianism emphasized human merit and downplayed original sin; Nestorianism proposed two distinct persons in Christ; Monophysitism taught a single nature in Christ. Ecumenical councils such as Nicaea and Chalcedon defined orthodoxy and rejected these positions, shaping subsequent church doctrine and structure. Some movements faded, while others persisted as separate churches or influenced later reform.

Outside Christianity, similar concerns about doctrinal boundaries appear in other faiths. In Islam, debates over religious innovations (bida) reflect a comparable effort to preserve doctrinal integrity. In modern pluralistic societies, the term “heresy” is largely historical or pejorative, though scholars study its role in enforcing authority and redefining communal identities.