The old religion (Catholicism) opposed by Protestantism has a structure, a system and an intermediary between god and man, so it can guarantee the realization of sacred values politically. The problem of the old religion is not "the unity of politics and religion", but "replacing politics with teaching" and establishing a power center outside political power. Trying to annex and replace politics leads to the monopoly of theocracy and oppression of human rights. In the old religion, God was in charge of everything. He entered the political arena through the church and took charge of political affairs, economic affairs, moral affairs, legal affairs, educational affairs and various social affairs. Although there is a God in Protestantism, God only exists in the individual's mind, and he has withdrawn from the political field and no longer cares about political and economic affairs. God has only become the object of personal "ultimate concern", which can only solve the problem of personal life belief, but not the political and economic problems. In this way, if the sacred value is not guaranteed by politics and its institutional arrangements, God will no longer have power and the western world will be extremely secular. (Because the institutional framework is power, without it, there is no power. Without power, people's selfish desires can't be restricted, and society is extremely secular. Therefore, although there is a God in western society now, God does not play a role in politics, in fact, there is no God. Therefore, in order to solve the disadvantages of extreme secularization in the western world, it is necessary to restore "the unity of politics and religion", which will repeat the mistake of theocracy oppressing human rights in history. This problem is difficult to solve under the framework of western culture. There is no doubt that China's tradition of combining politics with customs is worth learning from the west.