The term is derived from the Greek hairesis, which means "choice" or "thing chosen." Traditionally, heresy was the sin of a baptized and professing Christian who denied a defined doctrine of the faith. Heresy is distinguished from apostasy, the abandonment of the church by one who denies the church's teaching; and from schism, the fracturing of the church's unity for reasons other than disagreement in basic doctrine. Many of the classical formulations of the Christian faith were made by the ecumenical councils in response to beliefs that were later judged to be heretical.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.