A timely passage from one of my favorite little books: The Excellent Empire: The Fall of Rome and the Triumph of the Church, by Jaroslav Pelikan (Harper & Row, 1987). Like many of my favorite books, it was recommended to me (in this case, actually, assigned) by Dr. Weinrich. I'm sorry to say that it has been out of print for a number of years now. But it's a fascinating book. Pelikan looks at Gibbon's Decline and Fall of the Roman Empire in comparison with several early Christian interpretations of Rome in the fourth and fifth centuries, including Augustine's City of God. This passage is from the chapter in which he takes up Augustine:
"Augustine did indeed join Eusebius, Socrates, and Sozomen [the Eastern Christian historians of the Church] in praising Constantine as a worshiper of the true God, and with them he attributed the political successes and military victories of this Christian emperor to the actions of God. But he said all of this only after he had pointed out a few paragraphs earlier that the God who ruled human history had granted power not only to the noble Augustus but also to the cruel Nero, and that 'he who gave it to the Christian Constantine gave it also to the apostate Julian' in accordance with his sovereign but hidden will.
"As for the Christian emperor Theodosius, of whom Socrates and Sozomen spoke so effusively, Augustine, after reciting various evidences of the emperor's devotion to Christ and to the orthodoxy of the church that made him 'a model Christian prince,' climaxed his own panegyric, by contrast with those of his Greek contemporaries in Constantinople, with a description of the ultimate proof of Theodosius's piety: his willingness, in the year 390, to prostrate himself in public penance before the discipline of the church after he had sinned, when, in Gibbon's words, 'the rigid Ambrose commanded Theodosius to retire before the rails, and taught him to know the difference between a king and a priest' — an incident about which Augustine would have known directly from his own 'father in Christ,' Bishop Ambrose of Milan.
"Thus Augustine found himself in the position of not being able either to condemn Old Rome altogether or to commend it unequivocally. He paid tribute to Cato both for his personal virtue, which Augustine judged to have come closest in his time to the true definition of virtue, and for his contribution to the Roman Republic. God had, according to Augustine, granted to the Romans 'the terrestrial glory of that most excellent empire' as a reward for their virtue. This was not the reward granted to the elect in the city of God, but it was a genuine reward nonetheless. And in the peroration to Book Two of the City of God he called upon the Romans to 'purge and perfect' their virtues by turning to the true God and forsaking their idols.
"On the other hand, it was the worship of these idols and the consequent excesses of ambition and vainglory that had vitiated the peace and justice to which Rome claimed to be devoted; and if justice was undermined, what was a kingdom but a glorified robber band?
"The swing of the pendulum at work in the decline and fall of the Roman Empire, in God's conferral of imperial power on Constantine the pious and then on Julian the apostate, was for Augustine a characteristic of the historical process. Within this historical process, the relation between the 'celestial glory' of the city of God and the 'terrestrial glory' of the city of earth was a dialectical one. . . . The 'two cities,' Augustine wrote, 'are entangled together in this world, and intermixed until the Last Judgment brings about their separation,' and their history together was a 'checkered' one. There was likewise a dialectic within the history of the earthly city itself, as was evident in the history of Rome'" (Pelikan, The Excellent Empire, 100-101).