The implication of what has been said is this: If Christians ask non-Christians merely to accept the gospels or some other part of Scripture as historically trustworthy documents, they are allowing the legitimacy and efficacy of the principle of autonomy. They are allowing that it is possible intelligently to identify and set in order the elements of human experience in history by means of the principle of autonomy. But if this were true, if by the principle of autonomy such identification and ordering could take place, there is no need for the idea of God speaking to men. It is just because man cannot speak intelligently to himself without God and because the sinner has sent God out of his life that God in condescending grace comes back to him. But he asks men to accept him at his word for what he is, the indispensable presupposition of all intelligent human predication.
– Cornelius Van Til, A Christian Theory of Knowledge p.228