How (Not) to Be Worldly: Tracing the Borders of the 'Earthly City'
In a similar vein—indeed, as a synonym for Mouw's point—you'll sometimes hear folks suggesting that Christians should be invested in the "earthly city," or that we are simultaneously citizens of both the heavenly city and the earthly city. Like Mouw's call to "holy worldliness," these affirmations of the "earthly city" are rightly meant to displace our lingering otherworldliness—pushing us to see that God is not only interested in saving souls from the city but desires to see the flourishing of the city.
The invocation and affirmation of "the earthly city" is meant to reflect Scripture's robust theology of creation and affirm our embodied, material, social, and cultural life. This is sound, biblical theology—and a much needed corrective to our otherworldly ways. However, because the history of the term means something different, talking about "the earthly city" in this way can be confusing.
The phrase "earthly city" is an ancient one, but you won't find it in Scripture. (That's not a problem in itself; the word Trinity isn't in Scripture either.) The phrase comes down to us from Augustine's magisterial work of cultural criticism, The City of God (civitas Dei, completed around 427 A.D.). In this work, Augustine distinguishes the "City of God" from what he variously describes as "the city of this world," the "earthly city," and the City of Man. These two cities or societies or "peoples" are marked by the standards by which they live: the earthly city lives by the standard of the flesh, whereas the City of God lives by the Spirit (14.1-4). What ultimately distinguishes the two are their loves: "We see then that the two cities were created by two kinds of love: the earthly city was created by self-love reaching the point of contempt for God, the Heavenly City by the love of God carried as far as contempt of self" (14.28).
For Augustine, then, the earthly city begins with the Fall, not with creation. The earthly city is not coincident with creation; it originates with sin. This is why Augustine sets the City of God in opposition to the earthly city: they are defined and animated by fundamentally different loves. So the earthly city should not be confused with the merely "temporal" city or the material world. It is not identical to the territory of creation; rather, for Augustine, the earthly city is a systemic—and disordered—configuration of creaturely life. However, this does not mean that Augustine cedes material, cultural, creaturely life entirely to the evil one. The City of God is not just otherworldly: the City of God is that "society" of people—that civitas—who are called to embody a foretaste of the social and cultural life that God desires for this world.