The Christian belongs not in the seclusion of a cloistered life but in the thick of foes. There is his commission, his work. ‘The Kingdom is to be in the midst of your enemies. And he who will not suffer this does not want to be of the Kingdom of Christ; he wants to be among friends, to sit among roses and lilies, not with the bad people but the devout people. O you blasphemers and betrayers of Christ! If Christ had done what you are doing who would ever have been spared?’
Bonhoeffer quoting Luther in Life Together, p. 17-18.