· Professor of Biblical and Quaker Studies, George Fox University1989–
· Visiting Professor/Researcher, Chapman University
· Visiting Professor/Researcher, Haverford College
· Visiting Professor/Researcher (DAAD Professor), Johannes Gutenberg University of Mainz
· Extraordinary Professor of Religion, North-West University, Potchefstroom, South Africa
· Visiting Professor/Researcher, Princeton Theological Seminary
· Visiting Professor/Researcher (Fulbright Specialist), Radboud University of Nijmegen
· Honorary Fellow, University of Edinburgh
· Visiting Professor/Researcher, Yale Divinity School