I am reading some sermons and letters written by Niemoller and Bonhoeffer while they were incarcerated, but I was wondering how members of the Confessing Church practiced Christianity outside of prison. Did members meet secretly? How did they avoid being caught? Can you suggest any further reading?
Check out Twisted Cross by Doris Bergen (UNC Press, 1996). A partial version is available on Google Books. I don't want to do the book a disservice with an insufficient summary.