- "An opinion of private men different from that of the catholick and orthodox church" [Johnson], c.1200, from O.Fr. heresie (12c.), from L. hæresis, "school of thought, philosophical sect," used by Christian writers for "unorthodox sect or doctrine," from Gk. hairesis "a taking or choosing, a choice," from haireisthai "take, seize," middle voice of hairein "to choose."
- Incredulity is the neglect of revealed truth or the willful refusal to assent to it. "Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and catholic faith, or it is likewise an obstinate doubt concerning the same; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Roman Pontiff or of communion with the members of the Church subject to him" (CIC, can. 751; emphasis added).