'Because he had the courage to make his passionate protest against a worldwide terror, Castellio's feud with Calvin must remain everlastingly memorable' Stefan Zweig saw sixteenth-century Geneva as a place gripped by heresy-hunting fanaticism and raging ideologies of violence. A world in which free-thinking humanists too often foresaw, and failed to protest, the disasters that draconian leaders would bring upon Europe. Theologian and writer Sebastian Castellio, however, did condemn the burning of 'heretics' as murder and advocated for religious tolerance, at great personal cost. Written in 1936 when Zweig himself had just fled the rise of Nazism, The Right to Heresy is the story of Castellio's feud with Calvinist doctrine, and an urgent polemic on individual sacrifices made, throughout history, in resistance to authoritarianism.