Philosophy in medieval times also covered thinking about the ideal city. What is remarkable about thinking about the ideal city, is that the main focus seems to arise from religious thinking again. The Bible forms a great source for political philosophy, as it kind of contains a description of an ideal society. The Ten Commandments for example have a lot of correspondence with the laws we still have nowadays. Especially for philosophers such as Augustine or Gregory, christian theology and the ideal city know a lot of similarities. What I think is interesting is that within the idea of the christian ideal city, there are still a lot of differences, partly due to the difference between the Old Testament and the New Testament. Despite the fact that the God described in both manuscripts is the same, the norms differ from each other.
In the Old Testament, there seem to be a lot more cruelties in the manuscript. Those cruelties are, according to the Bible, allowed by God. The New Testament however seems to be written more from a positive view, and therefore has more humane norms in my opinion. A very actual example of this is, I think, the case of Black Lives Matter. In the Old Testament, one can find very racist statements when it comes to this. It could be that, from this idea of an ideal city, based on the Old Testament, groups have formed that do approve of these kinds of ideas. I think one can barely call this an ideal city. But, I think that the ideas that are in the New Testament are more rational to hold onto for forming an idea on what an ideal city would look like. Therefore, I think creating an ideal city based on religion is not per se rational. The most important thing, in my opinion, is that you base your decisions on morality.
Medieval Philosophy Blog 