What changed the thinking from magic and mysticism to reason and truth, opening the way to thinking about government?

The correct answer should be enlightenment. During the enlightenment period it became the norm to abandon the the mystical and spiritual ideas and focus on science and education and improving the government. They were focused by works of political realism like Machiavelli, Hobbes, Locke, Rousseau, and similar political realists.

Militarism is the answer.