Around the time when St. Augustine wrote City Of God. Many leaders felt the only way to find peace is through war. These leaders had their own plan on how to find peace.
The only problem with that was when you have more than one person trying to find peace you get a clash of opinions. Which will quickly escalate to war, so in essence these leaders are giving their opinion on how to find peace, resulting in a difference of opinion. St. Augustine in the mist of all this violence writes a book not intended for the public to see. He writes City of God as a guide to find peace. In order to find peace you have to love God, if you love God you will love yourself, if you love yourself then you will love your neighbor.
When that happens you will have the city of God. Peace can not be found on earth according to St. Augustine, peace is found in eternal life. The thing that separates St. Augustine from all these other leaders is the leaders are giving an opinion on how to find peace.
St. Augustine uses what the bible says as the guideline for peace. The best part about City of God, St. Augustine hides behind the bible to get his opinion out. He sets up a great guide on how to find peace but leaves spaces in the path to get to peace. The spaces represent Christianity because St.
Augustine is not trying force religion on people but show how following God will lead to peace. Peace on earth will never happen if man continues to have free will. Free will causes man to always have some sort of hatred for his self, and neighbor. That is why St. Augustine's work was never intended to become such a big religious document.