<P>"Ultimately," or so H. Richard Niebuhr wrote as early as 1929, "the problem of church and world involves us in a paradox; unless the church accommodates itself to the world, it becomes sterile inwardly and outwardly; unless it transcends the world, it becomes indistinguishable from the world and loses its effectiveness no less surely." In the same context he went on to state: "The rhythm of approach and withdrawal need not be like the swinging of the pendulum, mere repetition without progress; it may be more like the rhythm of the waves that wash upon the beach; each succeeding wave advances a little farther into the world with its cleansing gospel before that gospel becomes sullied with the earth."</P><P>Niebuhr's thought on the paradox of church and world is an essential piece of our understanding of twentieth-century theology in America. In this volume, Jon Diefenthaler collects for the first time over forty writings that trace the lineage of Niebuhr's thought, presents them in a single place, and makes a case for their enduring value in a post-church religious environment.</P>