Augustine ends book 18 with this:
“Thus far, we have depicted, to the extent that seemed sufficient, the mortal course of the two cities, the Heavenly and the earthly, which are mingled together from the beginning to the end. One of them, the earthly, has made for itself such false gods as it wished, from whatever source it chose – even creating them out of men – in order to serve them with sacrifices. But the other, the Heavenly, a pilgrim in this world, does not make false gods. Rather, that City is itself made by the true God, and is itself to be His true sacrifice. Both cities alike make use of the good things, or are afflicted with the evils, of this temporal state; but they do so with a different faith, a different hope, a different love, until they are separated by the final judgment, and each receives its own end, to which there is no end.”
I think this may be the clearest statement that he has made so far on the nature and existence of the two cities. They are mingled together for now, the one is a pilgrim city, the other makes false gods, the earthly makes sacrifices to false gods while the Heavenly is a sacrifice to the true God, the two cities have separate faiths, hopes, and loves, and they have different ends. Any of these points could make an interesting post. In their mingling, the two cities can be hard to tell apart – how do I know the citizen of one city versus the citizen of the other? It’s only truly evident when things get separated out at the final judgment. So, we can treat all others with love and grace and call them to godliness and dignity – after all, even the worst people are under threat of being transformed by God’s powerful grace.
Also, the earthly city makes false gods – we’ve seen a few of the false gods of our culture through the last nine months – and then sacrifices to those false gods. It is amazing how quick and disturbing it can be to watch someone go from starting to believe false gods to sacrificing significant things to those gods. Marriages, children, sense of self, love for others, etc – anything can become a potential sacrifice when a hungry god needs worship. It reminds me of the theorist from Dostoevsky’s Demons, who argues that to care for the Russian people and give them the most freedom, the Revolution needed to kill and enslave large majorities of Russia (written, of course, well before the actual Bolshevik Revolution, which attempted to accomplish just those ends by just those methods). In the City of God, love for God and others leads to the sacrifice of the self. We become the sacrifice, for the sake of God and others. The mystical and spiritual implications of this kind of sacrifice are astounding, but as we give of ourselves, we become more fully realized human persons. As we sacrifice, we become more godlike (in the sense of gaining divine union with Christ by the power of the Spirit). Every person in deep, intimate relationship knows something about this – the more we hang onto ourselves, the more we lose both ourselves and the intimacy that we want. But the more we pour ourselves out for another, the more we find out who and what we truly are and how God made us to become.
And then, loves. The two cities have different (faiths, hopes, and) loves. The one loves the self and the other loves God. The culture in which I live has now codified the concept of the self as final authority. The self has gone from “the thing I love” to “the thing that controls me”, and the self has no boundaries or purposes, it just is. I can now self-define my desires – except that desires, as every philosopher through human history knows, end up controlling the self. I will become a nothing with no end or purpose, no community, and no meaning. This seems to be the goal of the city of man, as expressed in our once great empire. In opposition stands the City of God, with its transforming, shaping love. God is the goal to which we are striving and the object (and subject) of our love. God Himself is love, and the ground in which our loves exist, and the only really worthy object of worship and adoring love. He makes us new, like Him, as we love. He draws us out of ourselves so that we can transcend the autonomous self and our love of self and invites us to participate in Him. Oh God, purify my loves and draw them to You, so that I may be made new and participate in full life in You!