“…The existence of the God of Christian theism and the conception of his counsel as controlling all things in the universe is the only presupposition which can account for the uniformity of nature which the scientist needs. But the best and only possible proof for the existence of such a God is that his existence is required for the uniformity of nature and for the coherence of all things in the world.”
I have to admit I’m not 100% in agreement with the words “only possible proof.” Perhaps it is exaggeration for effect. Anyway, Van Til went on:
“We cannot prove the existence of beams underneath a floor if by proof me mean that they must be ascertainable in the way that we can see the chairs and tables of the room. But the very idea of a floor as the support of tables and chairs requires the idea of beams that are underneath. But there would be no floor if no beams were underneath. Thus there is absolutely certain proof for the existence of God and the truth of Christian theism. Even non-Christians presuppose its truth while they verbally reject it. They need to presuppose the truth of Christian theism in order to account for their own accomplishments.”
You can find this quote in chapter four of Christian Apologetics by C. Van Til.