When Christianity came into the world the task was simply to proclaim Christianity. The same is the case wherever Christianity is introduced into a country the religion of which is not Christianity.
In "Christendom" the situation is a different one. What we have before us is not Christianity but a prodigious illusion, and the people are not pagans but live in the blissful conceit that they are Christians. So if in this situation Christianity is to be introduced, first of all the illusion must be disposed of.