How did The City of God respond to pagan criticism of Christianity?

In The City of God (De civitate Dei contra paganos), St. Augustine responded to pagan critics who blamed the 410 CE sack of Rome by Alaric and his forces on the abandonment of traditional pagan worship in favor of Christianity.12

Augustine’s defense employed several key arguments:

• Refutation of Pagan Claims: In the first 10 books, he systematically refuted the notion that pagan gods possessed divine power or were responsible for Rome’s past prosperity.12
• Moral Decay: He argued that Rome’s fall was not caused by the rise of Christianity but was instead the result of internal moral decay.1
• Spiritual Irrelevance: He asserted that the sack of the city held no true spiritual significance. He "dethroned" Rome, arguing that the earthly city is inherently doomed to disarray and that the only true home for Christians is the heavenly Jerusalem.2
• Christianity as a Savior: Contrary to his critics, Augustine maintained that Christianity actually saved Rome from complete destruction.1

Ultimately, he framed human history as a conflict between two symbolic "cities"—the City of God and the City of Man—reorienting the focus of believers away from worldly empires toward eternal salvation.123