Here is a good analysis in part of Today’s Religious Left. There is a brief history of the Social Gospel movement in America. Christopher H. Evans, the author, comes to this conclusion:
Can the religious left achieve the public status of the religious right? The theme of “social salvation” that was critical to Walter Rauschenbusch, A.J. Muste and Martin Luther King Jr. might, I believe, very well galvanize the activism of a new generation of religious progressives.
Read full article here.