The website "Political Affairs" has a review of Gary Dorrien's new book "Social Ethics in the Making: Interpreting an American Tradition." The book has a lot to say about Neibuhr, as the review notes:
Reinhold Niebuhr in the early ‘30s ridiculed the Social Gospel in his classic Moral Man and Immoral Society, which ushered in what Niebuhr called “Christian realism.” In the years of the Great Depression, this premier social ethicist pushed aside the optimism of the Social Gospel for the language of sin, power politics, transcendence and realism. He made the case that individuals might operate with altruistic motives, but society is made up of classes and groups who have clashing interests. In this howling arena, where each group demands to be heard and seeks power, the voice of Jesus calling for selfless love may only be a future vision, and the best we can realistically end up with is “rough justice,” which is the compromise amid countervailing power relations. Reform is possible, but it comes through struggle between capital, labor, and an assertive national government.
Niebuhr in these early days was an ardent socialist, but later, upon giving up Marxism, he adopted a welfare state realism in the Roosevelt era that put him in the mainstream of liberal democratic politics. He was, among other things, a co-founder of Americans for Democratic Action. In domestic politics, Christian realism was a strategy of balance-of-power relations between capital, labor, and assertive national government. As an aside, Walter Reuther, the union leader, was influenced by Niebuhr’s thinking, and Barack Obama is well-read in Niebuhr’s writings.
Internationally, Niebuhrian realism was a theory of balance-of-power interrelations among nations, which American strategists applied particularly to the USSR. This legacy was toxic. In defense of Niebuhr, he said that he hated that Cold War ideologues considered themselves Niebuhrian. With the fall of the Soviet Union, the neo-conservative ideologues promoted imperialist expansionism, a rationale that led the U.S. into, among other things, the fiasco in Iraq. This neo-con adventurism is the sorriest misuse of Niebuhr’s thought. It should be said, however, that Niebuhr’s persistent prophetic public call to stop fascist tyranny prior to World War II is one of the high points of the social ethical tradition.