I have not read this book, so this is really just a comment, but I have recently read the excellent work Why Niebuhr Now? by the late historian John Patrick Diggins. Why Niebuhr Now?
I recently read The Pragmatic God - On the Nihilism of Reinhold Niebuhr, The Pragmatic God (American University Studies. Series VII. Theology and Religion) a book that, strangely, has been universally ignored by scholars in history, philosophy, and religion. Ausmus contends that the logical consequence of Niebuhr's thought is nihilism, a rather serious charge to lodge against a Christian theologian and preacher.
Why has this work, published in 1990, been ignored?
I suspect that Niebuhr scholars and others fear that accepting the challenge to examine Ausmus' thesis may just disclose some nihilism in their thought.