The Social Gospel Movement was founded by Walter Rauschenbusch who did criticize the individualistic and pietistic conservativism of the late 19th Century. What Ben will not tell you is that 19th Century conservativism was premillienial and committed to biblical literalism, and thus it could not address the abject poverty, malnutrition, and rampant disease of the smoke-belching industrial era beyond telling poor people to wait for their reward in heaven or for Jesus to return. Rauschenbusch was a pastor in the "Hell's Kitchen" neighborhood of New York. He worked on the front lines of the human condition where conservative Christians feared to tread.
Ben will also not tell you what the church historians like Robert Handy will:
[T]he deeply religious orientation of [Rauschenbusch's] life was not shaken [by the Social Gospel] but deepened. He remained always an "evangelical liberal," influenced by liberal scholarship [especially critical scholarship in biblical studies] but grasped by a personally profound Christianity.In fact, the Social Gospel is criticized by other progressive theologies for being too sentimental and optimistic about the human capacity to overcome sin. It's a criticism that can also be leveled at contemporary conservatives (like Ben Cunningham), whose faith in markets bar acknowledgement of the capacity of market relations (which are also social and collective) to misuse, abuse, and destroy people.
Finally, Ben's insinutation of an unadulterated Christian theology of which liberal theology is not a part will lead him not to tell you that conservatives amalgamate and assimilate non-Christian elements in their theologies, too, because a literal doctrine of the Bible is impossible without making some qualifications and compromises.
Instead, Ben puts words into the mouths of Social Gospelers that they never would have uttered because it is politically expedient for the anti-revenue mob to discredit mobilized progressive Christians with half-truths about who they are and what they want to "steal."