Heresy

n. unorthodox religious belief; belief or idea which is in opposition to established views

Heresy, according to the Oxford English Dictionary, is a "theological or religious opinion or doctrine maintained in opposition, or held to be contrary, to the Roman Catholic or Orthodox doctrine of the Christian Church, or, by extension, to that of any church, creed, or religious system, considered as orthodox. By extension, heresy is an opinion or doctrine in philosophy, politics, science, art, etc., at variance with those generally accepted as authoritative." The study of heresy is heresiology. The founder of a heresy is called a Heresiarch.
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Noun
1. any opinions or doctrines at variance with the official or orthodox position
(synonym) unorthodoxy, heterodoxy
(hypernym) orientation
(hyponym) iconoclasm
2. a belief that rejects the orthodox tenets of a religion
(synonym) unorthodoxy
(hypernym) unbelief, disbelief
(hyponym) Arianism

(n.)
Religious opinion opposed to the authorized doctrinal standards of any particular church, especially when tending to promote schism or separation; lack of orthodox or sound belief; rejection of, or erroneous belief in regard to, some fundamental religious doctrine or truth; heterodoxy.
  

(n.)
An opinion held in opposition to the established or commonly received doctrine, and tending to promote a division or party, as in politics, literature, philosophy, etc.; -- usually, but not necessarily, said in reproach.
  

(n.)
An offense against Christianity, consisting in a denial of some essential doctrine, which denial is publicly avowed, and obstinately maintained.
  

An opinion held in opposition to the orthodox doctrine in the Christian church, a crime by medieval law punishable by death. Heretical opinions were examined by church courts , which could pass sentence and carry out the resulting justice. Notable examples of medieval heresies were the teachings of John Wycliffe, the teachings of the Lollards. The Inquisition was instituted in 13th century France, a tool used during the 14th century to purge the Templars from their extensive holdings in France and in most of Europe, most of their members being burned.