Reinhold Niebuhr's "Christian realism" combined theological insights with moral and political reflection, helping to guide society through its struggles for peace and justice during the mid-twentieth century. Without illusion or despair, he illuminated the possibilities and the limits of human existence. His perspective remains relevant for the problems and issues of our own time. This extensively researched intellectual and personal biography profiles Niebuhr's development and his role as a leading theologian, social philosopher, and political journalist. Brown concludes with an appraisal of Niebhur's legacy a legacy that continues to influence public discourse and religious life in the twenty-first century.