He was that rare thing, an American evangelical on the political left. Years ago, I read his book "20 hot potatoes Christians are afraid to touch". I wrote to him complimenting him on it, and got a very friendly reply.
https://en.wikipedia.org/wiki/Tony_Campolo
I remember Tony Campolo from my Greenbelt days. It was the time also of Ron Sider and Rich Christians in an age of hunger I recall.