(As for liberal christian authors I'd rather get to know the much more radical John Shelby Spong, who actually shaped my beliefs while I was a christian)
I've been to church with Spong (my father is from the town in North Jersey where he lives). My impression of him is that you either find both the man and his theology interesting and engaging, or you find them both boring and obnoxious as hell. I fall into the latter category.
Yeah, I don't think Spong is the best example of liberal Christianity, either. Maybe an example of liberal Christianity taken absurdly far (emphasis on the "liberal" part while de-emphasizing the Christian part
).