At the outset it ought to be clearly observed that every system of thought necessarily has a certain method of its own. Usually this fact is overlooked. It is taken for granted that everybody begins in the same way with an examination of the facts, and that the differences between systems come only as a result of such investigations. Yet this is not actually the case. It could not actually be the case.
In the first place, this could not be the case with a Christian. His fundamental and determining fact is the fact of God’s existence. That is his final conclusion. But that must also be his starting point. If the Christian is right in his final conclusion about God, then he would not even get into touch with any fact unless it were through the medium of God. And since man has, through the fall in Adam, become a sinner, man cannot know and therefore love God except through Christ the Mediator. And it is in Scripture alone that he learns about this Mediator. Scripture is the Word of Christ, the Son of God and Son of man. No sinner knows anything truly except he knows Christ, and no one knows Christ truly unless the Holy Ghost, the Spirit sent by the Father and the Son, regenerates him. If all things must be seen “in God” to be seen truly, one could look ever so long elsewhere without ever seeing a fact as it really is.
If I must look through a telescope to see a distant star, I cannot first look at the star to see whether there is a telescope through which alone I could see it. If I must look through a microscope to see a germ, I cannot first look at the germ with the naked eye to see if there is a microscope through which alone I can see it. If it were a question of seeing something with the naked eye and seeing the same object more clearly through a telescope or a microscope, the matter would be different. We may see a landscape dimly with the naked eye and then turn to look at it through a telescope and see it more clearly. But such is not the case with the Christian position. According to it, nothing at all can be known truly of any fact unless it be known through and by way of man’s knowledge of God.
– Cornelius Van Til, A Survey of Christian Epistemology p.4-5