The aseity of God is the ground for knowledge.
The narrative of the Fall demonstrates that attempted neutrality denies, at the outset, the possibility that the Christian worldview can be correct; the assumption that I determine truth makes genuine knowledge of the truth impossible. The problems run even deeper; denying the aseity of God not only denies the unbeliever access to the truth, but also denies him any ability to construct even a coherent facsimile of truth (an a truth).
The ultimate problem with unbelieving thought is that, whatever the specifics of his system, the unbeliever is committed to his own final authority; this is the principle of autonomy. His commitment to autonomy presents the unbeliever with an unsolvable problem: what he doesn’t know is ultimately and finally unknown. The consequence of this is that everything the unbeliever knows might, at any moment, be utterly overturned by the next thing he learns. All of his knowledge, then, is ultimately and finally uncertain.
The unbeliever who understands this problem may claim to resign himself to this uncertainty; this is (broadly speaking) the postmodern position. However, such a commitment is utterly unlivable; if he is correct, the relativist cannot even defend his relativism.
On the Christian worldview, however, God knows all truths, and all the relationships between truths, because all reality is what it is because God has spoken it that way. This provides a transcendent standard for truth.
As a Christian, I am quite willing to acknowledge that my understanding of the truth will be deficient; in fact, a central element of Christian theology is that God himself is incomprehensible. However, for the Christian, what is mystery for me is never ultimate mystery, because God knows; the universe and all it contains is ultimately rational because it was created by a personal, rational God.
Therefore, God’s knowing of all things provides an unchangeable, transcendent standard for knowledge. The Christian has the resources, within his worldview, to insist that this that God has revealed is true, and that assertions contrary to God’s mind are worthy of the epistemic condemnation of false.