The City of God (De Civitate Dei‪)‬

The City of God (Latin: De Civitate Dei, also known as
De Civitate Dei contra Paganos, "The City of God against the Pagans") is
a book written in Latin by Augustine of Hippo in the early 5th century, dealing
with issues concerning God, martyrdom, Jews, and other Christian
philosophies.

Augustine wrote the treatise to explain Christianity's relationship with
competing religions and philosophies, and to the Roman government with which it
was increasingly intertwined. It was written soon after Rome was sacked by the
Visigoths in 410. This event left Romans in a deep state of shock, and many saw
it as punishment for abandoning their Roman religion. It was in this atmosphere
that Augustine set out to provide a consolation of Christianity, writing that,
even if the earthly rule of the empire was imperilled, it was the City of God
that would ultimately triumph — symbolically, Augustine's eyes were fixed on
heaven, a theme repeated in many Christian works of Late Antiquity.

— Excerpted from Wikipedia, the free encyclopedia.