Men in general are, therefore, truth suppressors. They are not those who are first of all without knowledge of the truth. They are indeed such, if one thinks of the knowledge that must come from Scripture. But they are first of all truth possessors, or truth-knowers, who have, by sinning, become truth suppressors. Having taken to themselves the right to define the nature of God and of themselves, they have mingled the idea of their new god with that of the God they know by virtue of their creation. In their natural theology, that is, in what, as sinful men, they set forth as their view about God, they never state the truth without adulteration. They do not completely succeed in suppressing the truth, but they never assert the truth without an overwhelming admixture of error. The god of the philosophers is never their Creator and the Creator of the universe. He is always of necessity bound up with his creation. Hence sinful unregenerate men never worship the true God as they ought. In practice they do not know him because when they think of him they, of necessity, think falsely of him; they always degrade him to the level of the creature.
– Cornelius Van Til, The Reformed Pastor and Modern Thought.
Coming now to the knowledge that man in paradise would have of God, we must notice first of all that there man would be able to reason correctly from nature to nature’s God. But the meaning of this fact should be taken in connection with what we have said when discussing the true theistic conception of physics. We may perhaps best bring out what we mean by saying that man could originally reason from nature to nature’s God by contrasting it to what has usually been meant by that statement. In the first place, when men say that we can reason from nature to nature’s God, they usually take for granted that nature as it exists today is normal, and that the human mind which contemplates it is normal. This is not true. Nature has had a veil cast over it on account of the sin of man, and the mind of man itself has been corrupted by sin. Accordingly, we must not, now that sin has entered into the world, separate natural theology from theological psychology. After sin has entered the world, no one of himself knows nature aright, and no one knows the soul of man aright. How then could man reason from nature to nature’s God and get anything but a distorted notion of God? The sort of natural theology that the sinner, who does not recognize himself as a sinner, makes is portrayed to us in the first chapter of Romans.
– Cornelius Van Til, An Introduction to Systematic Theology p.133