For both Luther and Bonhoeffer God enters into and dwells in the world through weakness and suffering, rather than divine authority or strength. This article explores the significance of Luther’s theologia crucis and Bonhoeffer’s treatment of ‘the weakness of the Word’ in Discipleship. Moreover, it draws out some of the implications of these themes for Christian mission today. What does it mean for Christians to witness to and engage the world in weakness? How does this free Christians from needing a fixed programme or governing ideal in their witness and evangelism?