Book excerpt: A primer on the current "Niebuhr revival" of the political left and right, this book traces the significance of Reinhold Niebuhr's thought for secular as well as deeply Christian minds. Placed in the context of religious and cultural history, Niebuhr's theological views deepen and challenge contemporary expertise on issues of war, peace, economic, and personal security. While rejecting cynical pessimism and naive optimism, Niebuhr's Christian realism reinvigorates age-old teachings of the Bible, St. Paul, Augustine, and Kierkegaard. His thought enriches present-day debates between science and religion and between atheists, agnostics, and believers. To live with Niebuhr's legacy is to combine critical acumen with humble self-awareness. It is to pursue a larger common good - for him, God-given - that is shared among individuals, nations, and the world community.