Director of Studies at the CNRS (PSL Research University Paris, Laboratoire d’Études sur les monothéismes) in France, he is Doctor of Islamic Studies. He specializes in intellectual history of Shia Islam, Islamic modernism in the nineteenth century, Islam and Europe and the issues related to the Muslim presence in a secular context. He received his Habilitation in 2004 and his PhD in 1996 both from the University of Freiburg. He is the author of Die Schia und die Koranfälschung(2001) and Islamic Ecumenism in the 20th century. The Azhar and Shiism between Rapprochement and Restraint (2004). He edited Islam. Einheit und Vielfalt einer Weltreligion (2016). He is the Editor of Die Welt des Islams (Brill).