The unhappy encounter between Anabaptists and Reformed in Wismar in 1553 is a striking example of how confusing the sixteenth-century religious landscape was. In the early 1550s a group of Anabaptists under the leadership of Menno Simons managed to live peacefully in the small German Hanseatic town Wismar. They met informally in the private homes of members of their community. Apparently Wismar’s authorities turned a blind eye toward this group of Anabaptists. This mode of peaceful coexistence between a predominantly Lutheran population and a minority of Anabaptist refugees came to an end when a group of Dutch Reformed refugees arrived in the city. Unlike the Anabaptists, these Reformed refugees were unwilling to compromise. They endeavored to establish their own ecclesiastical organization and claimed their own church building to worship God in a pure Reformed manner.

Few figures from the Reformation era have remained as divisive as John Calvin. Whether because of Calvin’s doctrine of predestination or his involvement in the execution of Michael Servetus in Geneva in 1553, his contemporary detractors found ample reason for dissension. Regarding the former, five-odd centuries have done little to ameliorate (and perhaps much to exacerbate) the prima facie severity of Calvin’s specific brand of predestination, which maintains that God foreordained multitudes to eternal damnation before the creation of the world. Anyone who has been tasked with explaining the reformer’s thoughts on this matter to undergraduates in a Christianity 101 course (or to an innocent bystander at the local watering hole) is keenly aware of its almost universal unattractiveness. This sentiment holds a fortiori for the execution of Servetus. Two key sixteenth-century figures, Jérôme-Hermès Bolsec and Sebastian Castellio, honed in on these two issues in a barrage of anti-Calvinist writings. In doing so, they painted the first broad strokes of what would prove to be an enduring image of Calvin as a dour and intransigent figure. Moreover, they forced Calvin and Geneva into a series of defensive responses that were formative in the process of confessionalization beginning in the 1550s, a crucial period for religious identity formation especially among Swiss Protestant churches.

The challenge of heresy is inherent to any claim of orthodoxy by the Christian Church. The New Testament already states that there must be heresies so that those who are genuine believers may be recognized.1 As deviation from the ecclesial norm of orthodoxy, heresy threatens the unity of the Church, and even the integrity of society at large, when Christianity is the official religion of the empire as it was from AD 380. Heresy was a revolution, an attack on the order of the world. While modern readers may be tempted to view heresy as some positive expression of individual creativity in matters of doctrine, perhaps an instance of freedom of speech, such ideas were alien to the early modern mind. The stereotype of the heretic was not a creative individual, but someone possessed by the devil, driven by pride, who hid his heresy under the cover of seeming piety. Of course, not all doctrinal errors, dissident beliefs, and practices, were heresies. Error became heresy by obstinate refusal to obey the Church, which had defined orthodox teaching and sought to correct errors. As Robert Grosseteste defined: “a heresy is an opinion chosen by human perception contrary to holy Scripture, publicly avowed and obstinately defended.”2