The City of God contrasts two cities: the City of God and the City of Man.
The City of God is the "city of heaven", the eternal Jerusalem on the next life.
The City of God is invisible to us here; it is not of this earth. It is of the other world.
With distinct overtones of Neo-Platonism he taught that life on earth was little more than an illusion, and only in the City of God would people who were just come to their final resting place.
In contrast, the City of Man was evil and destined to decline and fall. It was a "city of earth" that by way of example had been seen in Rome and its Empire.
Although seeing the City of Man as evil, Augustine nevertheless realised that for as long as he was on this earth he was a citizen of that world.
He stipulated that, although the "city of earth" was the very opposite of the "city of heaven," it was a reality that people must face.
He wished that people engage the City of Man not just as a an experience of pain, but as an opportunity for Christian activity.
Christians were not to reject the world entirely, but instead must try to reform it to fit more of a Christian pattern.
He said that activities usually part of the City of Man - such as warfare, economic activity, education, and the rearing of children - should all be conducted in a Christian spirit.
He declared that the "city" - the next empire - that arose from the ruins and emulate Rome should be based upon Christian principles. (And the Christendom that came as a Middle Ages response to his call disappointed in this regard.)
In accordance with his world view that is centred on God, Augustine regarded the City of Man as evil, imperfect, and of no consequence in comparison to the City of God.
Even so, he accepted that it was not about to disappear and be replaced by a perfect Kingdom of God on earth.
(Continued on the next page.)