noun
1. a religious belief or doctrine not in keeping with the established doctrine of a church, esp. the rejection of or dissent from any aspect of Roman Catholic Church dogma by a baptized church member.
The view that the sun rather than the earth might be the center of the universe was considered heresy by many in the seventeenth century.
2. any opinion or belief that challenges deeply established social, academic, political, or religious views.
This notion that disease could be caused by microbes was heresy.