But the truth of propositions must be inquired into in the sacred books of the Church.
For purposes of this post, what I am interested in is the phrase “sacred books of the Church.” St. Augustine does not appear to hold to a view of the Scripture as something that is utterly distinct from the Church. Rather, it seems that he considers them as two things that go together: Scripture and the Church, so that the Bible is understood as belonging to the Church. This doesn’t seem to me to be the sort of thing that a Protestant would say: “the church’s Bible.” But it is the sort of thing that Augustine was willing to say by way of an apparent recognition that the two go together.
This seems to be consistent with a Catholic view, inasmuch as the Church insists that Scripture, Tradition, and the Magisterium “go together.”