 I am grateful to the following for extremely useful comments on previous versions of this entry, and for general discussions of Luther that have helped shape the views expressed herein: Maria Rosa Antognazza, David Bagchi, David Batho, Ryan Byerly, Sophie Grace Chappell, Benjamin Crowe, Theodor Dieter, Josh Furnal, Daphne Hampson, Susanne Herrmann-Sinai, Iona Hine, Bo Christian Holm, Volker Leppin, Wayne Martin, Alister McGrath, John Monfasani, Kees van Kooten Niekerk, Rory Phillips, Simon Podmore, Bjørn Rabjerg, Richard Rex, Daniel Roche, and Joe Saunders.