The last thing Kennedy says in Chapter 7 is, "Augustine had made it possible for Christians to appreciate and teach eloquence without associating it with paganism, and in so doing permanently enriched Christian literature and criticism." This seems true, as Kennedy knows his stuff, but it belies the reason that Augustine and other early church fathers brought rhetoric in-
I argue that once you learn rhetoric and eloquence, it's tough to shake. You don't just go from being a good speaker to being a bad speaker by force of will. The rules instilled into your communication are similarly bound, I think- I still find myself writing in 3s, using remnants of the five paragraph essay. The early Christian leaders had already been taught rhetoric, and I imagine that many of them had to fight off the criticism that their eloquence, derived from pagan sources, was inherently un-Christian (Kennedy notes that Augustine had to do this in Against Cresconius). It seems like it was a matter of justifying the rhetoric of getting kicked out of the church, so I find it hard to believe that Augustine was entirely acting for the future of Christianity when he made such strides for rhetoric.