Luther and Calvin also relied on the Fathers, although they did not put as much stock in their authority as Catholics did. Both Reformers and the Catholic theologian Jansen put too much stress on Augustine’s views, and not enough on those of the Greek Fathers.
As for the Greek Fathers, without St. Athanasius we would not have the Nicene creed; that is no small thing. We owe him a debt at least as big as that which we owe to Augustine. An Arian church would have been every bit as unrecognizable as a Pelagian church.