 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, Fabian Freyenhagen, Josh Furnal, Daphne Hampson, Susanne Hermann-Sinai, Iona Hine, Bo Christian Holm, Stephen Houlgate, Roderick Howlett, Volker Leppin, Wayne Martin, Alister McGrath, John Monfasani, Kees van Kooten Niekerk, Rory Phillips, Simon Podmore, Bjørn Rabjerg, Richard Rex, Daniel Roche, Joe Saunders, and Dan Watts.