Besides distinguishing between two cities: the city of God and the city of man, Augustine also pays close attention to the differences between the members of these two cities. By examining the nature of the populace once can gain a clearer view of the ends towards which each of these two cities strive.
Augustine refers to those citizens of the city of God who are currently living on earth as pilgrims, highlighting the fact that they are looking forward to something other than the current state of affairs in which they find themselves. Nevertheless, while they are living on earth, the goods and pursuits of the citizens of both cities are intricately related. Both cities desire certain types of peace and harmony. The city of man strives after “earthly peace in the goods and advantages which belong to this temporal life.” The citizens of the city of God who are on pilgrimage on earth “[look] forward to the blessings which are promises as eternal in the life to come.”
Further, the pilgrims make use of the same goods and advantages as the city of men, only they do so to the end of achieving a lasting and eternal peace. The earthly city establishes civil law with the aim of maintaining concord among the citizens so that they might go about pursing their happiness in earthly goods.
Likewise, by living under the rule of these laws and “[making] use of the peace of Babylon,” the pilgrims are able to benefit from the establishment of order and temporal goods. For the things sought by the earthly city are still good, albeit lesser goods than the supreme goodness of God which is sought by the city of God. Therefore, the pilgrims are obligated to contribute to the earthly peace as much as possible, only dissenting in the face of laws that prohibit the fulfillment of religious duties. Further, they may continually strive to bring about true justice (giving God and men their dues) in their state. The only caveat he extends is that they not become enamored with the temporal goods and pleasures found in the earthly city and turn from God and worship of Him alone.
The importance of being enamored only with God is seen in the ultimate ends of the two cities. Augustine unambiguously states that “[the city of God] is predestined to reign in eternity with God, and the [city of man] will undergo eternal punishment with the devil.” Augustine has a linear conception of history that began with God creating and will end with God judging the world. From the Fall until judgment, the two cities live together and pursue their various ends; the earthly city pursues temporal things and the heavenly city pursues eternal things (often using temporal things for a spiritual end). Each city has a determined purpose from the beginning, and although the two are intermingled for a time on earth, their purposes are never confused or identified with one another. Augustine’s conception of the two cities and their ultimate ends draws a clear distinction between the spiritual and temporal realms. This distinction is not so severe as to keep the two realms from interacting quite significantly with each other, especially in the pursuit of just, peaceful, and well-ordered societies, and yet it is still a clear distinction that keeps the realms separate and does not confuse their purposes, identities, or ends. Look for the Islamic division of religious and political realms next...