Noun
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.
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.
An offense against Christianity, consisting in a denial of some essential doctrine, which denial is publicly avowed, and obstinately maintained.
Source: Webster's dictionaryHeresy is another word for freedom of thought. Graham Greene
Progress, that great heresy of degenerates. Charles Baudelaire
In the end it is worse to suppress dissent than to run the risk of heresy. Learned Hand
Heresy is the school of pride. English Proverb
Heresy may be easier kept out than shook off. English Proverb
With the first wife is matrimony, the second company, the third heresy. Italian Proverb