It's worth mentioning here that Gregory Baum was once an Augustinian priest, as was Martin Luther.  And like Luther, Baum was German-born (Berlin), but emigrated to Canada.  While he was still active in the Catholic priesthood, in the late '60s, I attended one of his ecumenical presentations, delivered at a Methodist seminary rather than at a nearby Catholic seminary with more ample facilities.  Seldom have I heard or seen a theologian of any denomination manifest a greater knowledge and love of his subject matter, or seen a speaker connect more vibrantly with his audience.  That he is still writing, in his '90s, is a welcome event and no surprise.