2013. “Gnostic and Manichean Interpretation.” Pages 584-604 in The New Cambridge History of the Bible. Vol. I: From the Beginnings to 600. Edited by J. Carleton Paget and J. Schaper. Cambridge: Cambridge University Press.

2012. “Christian Gnostics and Greek Philosophy in the Second Century.” Early Christianity 3: 349-377

2010. “Christianity as Philosophy: Problems and Perspectives of an Ancient Intellectual Project.”  Vigiliae Christianae 64: 160-88

2007. “Western Christianities.” Pages 9-51 in The Cambridge History of Christianity. Vol. 2: Constantine to c.600. Edited by A. Casiday and F. W. Norris. Cambridge: Cambridge University Press.

2007. Pelagius – Portrait of a Christian Teacher in Late Antiquity. The Alexander Souter Memorial Lectures 1. Aberdeen: University of Aberdeen.

2006. “Arius reconsidered (Part 1), ZAC 9: 524-560.

2006. “Arius reconsidered (Part 2).” ZAC 10: 121-157.

2005. “Sethians.” Pages 1063-1069 in Dictionary of Gnosis and Western Esotericism. Edited by W. J. Hanegraaff. Leiden: Brill.

2003. “Valentinian Variations on LK 12,8-9 / Mt 10,32.” Vigiliae Christianae 57: 437-455

2002. “Did Marcion distinguish between a just god and a good god?, Pages 131-146 in Marcion und seine kirchengeschichtliche Wirkung / Marcion and His Impact on Church History. Edited by G. May and K. Greschat. Berlin: Walter de Gruyter.

2000. “Religious Truth, Dissimulation, and Deception in Late Antique Christianity.” Pages 287-304 in Double Standards in the Ancient and Medieval World. Edited by K. Pollmann. Göttingen: Duehrkohp & Radicke. (paperback)