"Augustine’s two ways of speaking of the city of God and the earthly city make
sense in light of the distinction among his readers. Carnal readers dominated
by the lust for domination will more likely have to be told that the city of God
is the Church because that holds out the best hope for taming their prideful
ambitions. They will hear that happiness consists not in politics but only
through submission to Christ and community in the Church. More virtuous
readers will learn that the two cities actually refer to the dominant loves and
that the two cities intermingle in the Church and the political city. The latter
group constitutes a greater hope that the political city might be more justly
governed." - John von Heyking, Augustine and Politics as Longing in the World