Heresy is any belief or theory that is strongly at variance with established beliefs or customs, particularly the accepted beliefs or religious law of a religious organization.[1][2] A heretic is a proponent of heresy.[1]
Heresy in Christianity, Judaism, and Islam has at times been met with censure ranging from excommunication to the death penalty.[3]
Heresy is distinct from apostasy, which is the explicit renunciation of one's religion, principles or cause;[4] and from blasphemy, which is an impious utterance or action concerning God or sacred things.[5] Heresiology is the study of heresy.