Christianity does not say monarchy is the proper form of government. In fact according to the book of Samuel, God only allowed them to have a king, and gave them one because they demanded one, but warned that it wasn't a good idea. The king was to be closely monitored and under stricter laws, and chosen by God. Even that didn't work, because time and time again they were still hopelessly corrupt. Even Solomon, who was said to be the wisest man on Earth like Socrates, didn't use his wisdom when he thought he could get away with things.

That's the Old Testament. The New Testament seems to oppose the material world itself.