I've been reading A Testament of Hope which is a compilation of sermons by the Rev. Martin Luther King, Jr. I also know he's a Baptist. (I even got to stand and preach for a minute in his pulpit last year!)
What I haven't seen is a lot of emphasis on the Gospel, but I'm not sure if that was a selection bias (since the book really is there to focus on his Social Gospel), or if that really is indicative of his preaching style.
Is there a good sermon that represents his view of salvation? (An altar call? A good theology? Bueller, Bueller!)