The City of God Against the Pagans by Augustine of Hippo, also known as Aurelius Augustinus, was a thesis on why the pagan gods of ancient Rome were not effective in guiding people and granting them divine protection. The work was a response to pagans within the Roman Empire who accused Christianity of weakening the once-mighty empire and insisted that the new Christian rulers of Rome had a mistake in converting the empire to Christianity. The rhetorical duel between the pagans and Augustine stemmed from the citizens' reaction to the sacking of Rome by the Germanic tribes.

In The City of God, Augustine argues that the famous Greek philosopher Plato had revolutionized the ancient Greeks' belief systems and way of thinking because the pagan deities of ancient Greece were anachronistic and illogical. In the same vein, Augustine's argument makes sense when criticizing the pagan beliefs of ancient Rome and illustrating why Christian theology and values are the logical replacements for pagan worship.

Augustine believed that Rome, in the era of the Holy Roman Empire, could be a beacon across the empire and beyond. He was essentially trying to argue that Christianity gave the Roman Empire a stronger reason to rule. Before, during the pagan eras, the Roman Empire focused on acquiring more territory, wealth, and power.

Augustine argued that, under the umbrella of Christianity, the Roman Empire becomes a figurative, and perhaps literal, satellite of God's kingdom (hence the title). Rome, thus, becomes a place of salvation and virtues. This is why the Vatican was established within the city of Rome.