This paper focuses on how truth and power have been combined in the history of Western Christianity, eventually leading to the sanctification of power and the power of truth. Once a certain truth is sanctified, it can easily be adopted as an absolute dogma and become a tool to destroy dissenters or even kill people, becoming a "ghost" wandering over the heads of the people. Therefore, the pursuit of truth is a legitimate act, but using the so-called truth as a tool to consolidate power and maintain dictatorship is not desirable.