Abstract

Medieval theologians took their concept of heresy mainly from the texts of Jerome and Augustine quoted in Gratian’s Decretum. Thomas Aquinas held that anyone w ho pertinaciously denies even a minor item of Church or Bible teaching falls into heresy. Ockham developed criteria for pertinacity and argued that a Christian, even if his or her opinions are actually in error, cannot be regarded as pertinacious simply for refusing to defer to the teaching of a pope