This article discusses how issues of doubt and scepticism were addressed during the history of the Reformation, citing as examples disagreements between Luther and Erasmus. It focuses on the less familiar figure Sebastian Castellio, whose disagreements with John Calvin put his life at risk. He took a stand against all the leading Reformers who understood themselves to be the chosen proclaimers of a single true Protestant teaching and considered every deviating opinion or critical question to be a betrayal of God's work and of God's renewed Church. His last, incomplete book, ‘On the Art of Doubting and of Believing, of Not Knowing and of Knowing’ was written in exile in Basel.
Daniela Koeppler was born in 1969. Her Dr. phil. dissertation was titled ‘Zelte der Begegnung’: Geschichte und theologische Bedeutung der Ständigen Konferenz von Juden, Christen und Muslimen in Europa (JCM) und der Internationalen Jüdisch-Christlichen Bibelwoche. She is a pastor in Hannover (Lower Saxony), and in charge of Christian–Jewish relationships in the Lutheran Church of Hannover.