It is necessary that Christians should remember that it is not the business of the Church to do the same thing as the State — to build a Kingdom like the other kingdoms of men, only better; nor to create a reign of earthly peace and justice. The Church exists to be the light of the world, and if it fulfills its function, the world is transformed in spite of all the obstacles that human powers place in the way. A secularist culture can only exist, so to speak, in the dark. It is a prison in which the human spirit confines itself when it is shut out of the wider world of reality. But as soon as the light comes, all the elaborate mechanism that has been constructed for living in the dark becomes useless. The recovery of spiritual vision gives man back his spiritual freedom. And hence the freedom of the Church is in the faith of the Church and the freedom of man is in the knowledge of God.
Christopher Dawson, Dynamics of World History, p. 273