Thanks for reading my mind. Other than the pompous pretense of a "cultured" world view, that article was astonishingly empty. Like anything else, "art" is shaped by its historical and material situation. And while there were Christians involved in the abolition and civil rights movements, as well as in organizing medical charities, there were also all manner of agnostics and atheists as well. Not to mention the believers who also struggled a great deal against all those things.
It certainly was a mixed bag. Neither side can claim exclusivity on any of those things you mentioned. However, it was Northern Christians who gave the abolition movement it's moral punch.