We accept this God upon Scriptural authority. In the Bible alone do we hear of such a God. Such a God, to be known at all, cannot be known otherwise than by virtue of His own voluntary revelation. He must therefore be known for what He is, and known to the extent that He is known, by authority alone. We do not first set out without God to find our highest philosophical concept in terms of which we think we can interpret reality and then call this highest concept divine. This was, as Windelband tells us, the process of the Greeks. This has been the process of all non-Christian thought. It is from this process of reasoning that we have been redeemed. On such a process of reasoning only a finite god can be discovered. It has been the nemesis of the history of the theistic proofs that this has been so frequently forgotten. Are we then left with a conflict between Faith and Reason? Have we no philosophical justification for the Christian position? Or are we to find a measure of satisfaction in the fact that others too, non-Christian scientists and philosophers as well as ourselves, have in the end to allow for some mystery in their system?
To all this we must humbly but confidently reply by saying that we have the best of philosophical justification for our position. It is not as though we are in a bad way and that we must seek for some comfort from others who are also in a bad way. We as Christians alone have a position that is philosophically defensible. The frank acceptance of our position on authority, which at first blush, because of our inveterate tendency to think along non-Christian lines, seems to involve the immediate and total rejection of all philosophy—this frank acceptance of authority is, philosophically, our very salvation. Psychologically, acceptance on authority precedes philosophical argument; but when, as epistemologically self-conscious grown-ups, we look into our own position, we discover that unless we may presuppose such a God as we have accepted on authority, the Moment will have no significance. The God that the philosophers of the ages have been looking for, a God in whom unity and diversity are equally ultimate, the “Unknown God,” is known to us by grace. It has been the quest of the ages to find an interpretative concept such as has been given us by grace.
– Cornelius Van Til, Common Grace and the Gospel p.14