My friend Brad East wrote with a partial dissent to something I say in this post:

When you say the City of God precedes the church, it seems to me you're making a semantic decision that determines your conceptual interpretation. Such a claim makes sense only if you have predetermined that “church” means something like “the visible institution begun at Pentecost and continued in the public apostolic succession of episcopal administration” (or whatever). But all kinds of Christian writers have used the term "church" to mean something different and larger than that. In which case it's not that the City of God isn't the church; it's that the church means something different than we often suppose in our colloquial speech.

Suppose “church” is coextensive with “the people of God,” which in turn is coextensive with “Abraham's children,” which in turn is coextensive with “God's children.” (You could add other convertible terms: “all the elect” and/or “all the saved” and/or “all who shall see God face to face.”) If that's true, then you no longer have to distinguish between “City of God” and “church,” arguing that in Augustine's or our usage the latter doesn't mean the former. Rather, the conceptual range of “city” clarifies and expands our ordinary, or at least theological, usage and definition of “church.” So that “the City of God is the church and vice versa” redraws the boundaries of the rather [crabbed] definition some of us presuppose when we use the word “church.” So that, further, Augustine is narrating the course of God's church from Adam/Abel to the Parousia and beyond into the new creation, it's just that Augustine is helping us to understand what “church” means, or should mean, in our concepts and speech. 

To which I responded: 

Let’s make a distinction between what we — seeking to speak rightly about God's Church — might want to say and what Augustine says. I’m just trying to understand Augustine, not make any claims myself. So what does he say about the relationship between City and Church? 

Well, he’s not perfectly consistent. At one point he speaks of “the City of God, that is to say, God’s Church” (XIII.16), but I think that’s a moment of carelessness. Much more often he speaks of the Church as the part of the City that hasn’t yet come into its heavenly inheritance, that is still wayfaring. He often says that the angels are the larger part of the City of God, and “with us they make one City of God…. Part of this City, the part which consists of us, is on pilgrimage; part of it, the part which consists of the angels, helps us on our way” (X.7). And the angels are not the children of Abraham, nor are they the “elect.” 

So I think on the Augustinian reading the City of God does precede the Church, because the angels (“all the company of Heaven”) precede the Fall, and it is with the Fall (exitus) that our pilgrimage (reditus) begins. Augustine believed, with virtually the whole Christian tradition, that (a) the serpent in the garden is to be identified with Satan and (b) Satan is a fallen angel. Q.E.D. 

He also speaks fairly often of those who are part of the visible Church, who share the sacraments with the rest of us, but who will not inherit eternal life (I.35).

So for all those reasons I think Augustine does tend to make a fairly clear distinction between the Church — which we might define as “the faithful among the visible ekklesia, those who are genuinely on pilgrimage towards God” — and the City of God, which is a larger and older entity of which the Church (as just defined) is a part. 

Reader, make your own decision!