The difference between believers and unbelievers as to knowledge is not so much in the matter of their knowledge as in the manner of knowing. Unbelievers, some of them, may know more and be able to say more of God, his perfections, and his will, than many believers; but they know nothing as they ought, nothing in a right manner, nothing spiritually and savingly, nothing with a holy, heavenly light. The excellency of a believer is, not that he has a large apprehension of things, but that what he does apprehend, which perhaps may be very little, he sees it in the light of the Spirit of God, in a saving, soul-transforming light; and this is that which gives us communion with God, and not prying thoughts or curious-raised notions.
John Owen, Of the Mortification of Sin in Believers in Kapic & Taylor (eds.), Overcoming Sin & Temptation (Crossway, 2006), p117
After Van Til’s brief discussion of Idealism, in his Introduction to Systematic Theology, he moves on to discuss the principium essendi of knowledge (p. 29). Van Til claims that all of our knowledge has its origin and foundation in God. The self-consciousness of God is necessary for us to know anything of Him. Indeed, our knowledge of any thing at all depends ultimately upon God’s own knowledge of that thing.
God’s knowledge of creation is archetypal in that His knowledge of things encompasses their essence as well as all their relations to other things. Since the works of creation are products of his own determination and will, the knowledge of God is immediate and He does not require discursive thought to infer or deduce new knowledge. His knowledge is comprehensive and perfect. All of God’s knowledge is present to His consciousness at the same time.
God’s knowledge of Himself is similarly comprehensive. God has no sub-consciousness, but is perfectly and completely self-conscious. He knows transparently and exhaustively His own reasons and purposes for acting, both amongst the members of the Godhead and in His dealings with His creatures. There is nothing in the being or acts of God that are not fully comprehended by Him.
It is this self-conscious knowing of God that allows man to obtain knowledge of Him. As Berkhof says:
“It is impossible to deduce a conscious creature from an unconscious God, a creature that knows God from a God that does not know Himself. We can find the principium of our theology only in a personal God, perfect in self-consciousness, as He freely, consciously, and truly reveals Himself.”
In other words, a self-conscious act of self-revelation of God is required for us to know Him. He actively reveals Himself, rather than passively allowing Himself to be discovered and observed by His creatures. This is why Berkhof follows Bavinck by asserting that “Pantheism [ie a god that lacks self-consciousness) is the death of theology”. A being that is not a self-conscious being cannot be a self-revealing being. Bavinck states that God “is knowable only because and insofar as he himself wants to be known.”