What is the theme in Bonhoeffer: Pastor, Martyr, Prophet, Spy by Eric Metaxas?

Another theme is the value of friendship and family. One of the work's secondary thematic considerations is the role friendship and family played in Bonhoeffer's life, work, and ever-evolving theological philosophy. The author makes this point very clear right from the beginning when, while setting the scene for Bonhoeffer's memorial service in London, he says those who prepared the service and who spoke at it were motivated as much by friendship and affection as they were by the desire to pay tribute to a Christian martyr. Then, from the first chapter on, the author repeatedly incorporates examples of how Bonhoeffer's family and friends influenced his life.