Claus Arnold is Professor of Medieval and Modern Church History in the Faculty of Catholic Theology at the University of Mainz. He studied Theology at Tübingen and Oxford and holds a STD from Frankfurt-Sankt Georgen. He received his habilitation in Church History at the University of Münster in 2003. From 2004 until 2014 he was a tenured professor of Church History at the Goethe University in Frankfurt am Main. His research interests include the Modernist Crisis in Catholicism and the history of the Roman Curia.