Never has there been such interest in heresy and the 'religious forbidden'. But what is heresy? Why has it been sprinkled with stardust in recent years? How did it originally develop? Are heresies liberating ideas that were ruthlessly suppressed? Or are they flawed visions of Christianity, abandoned because of their inadequacies? In Heresy, historian and theologian Alister McGrath reveals the surprising history of his subject, presenting an orthodoxy that will equip the Church to meet the challenge from renewed forms of heresy today.