Incomprehensibility is not an essential attribute of God. That is, God is not incomprehensible to Himself, and the Persons of the Godhead are not incomprehensible to one another. The Spirit searcheth all things, yea, the deep things of God (1 Corinthians 2:10). Incomprehensibility, then, is not an intrinsic attribute of God. It has reference only to the knowledge that the creature may have of God. It is out of the very nature of the Creator/creature relation that God is incomprehensible to His creatures. It is God’s Godhood or divinity that makes Him incomprehensible to all finite creatures.
We must distinguish the incomprehensibility of God from our inability to know the universe exhaustively. Our finite understanding is not capable of a full and exhaustive understanding of all the created universe. There is a difference between the incomprehensibility of God and that of the created universe. God is absolutely incomprehensible, whereas created reality is relatively incomprehensible. God’s incomprehensibility is original or primary, that of the created universe is derived or secondary. Ultimately, the incomprehensibility of the universe is derived from the fact that the God of all wisdom has created it all. It is, therefore, revelatory of the attributes of God. Thus, the universe reflects the incomprehensibility of God in that it is also incomprehensible to man.
The incomprehensibility of God is absolute. That is, God remains incomprehensible, even with our increased knowledge of Him. He is eternally incomprehensible to the created mind. The Creator/creature distinction always exists. The more we know of Him, the more we understand that He is incomprehensible. Paul exclaims, on this, after he himself has received deep insight into the revelation of God concerning His eternal decrees: O, the depths of the riches of God, both of the wisdom and knowledge. How unsearchable are His judgments, and His ways past finding out (Romans 11:33).
The revelation of God is incomprehensible in the same sense that the created universe is incomprehensible. We must be careful not to assume that, because He has not revealed all things to us, that there are areas which He cannot reveal to us, for He has revealed unto us much respecting Himself and His own internal relations. To assume that some areas are beyond the realm of revelation would be to assume that they were more ultimate than His essential being and trinitarian relationships, which He has revealed. This would be blasphemous, for these are the most ultimate of truths. The incomprehensibility of revelation arises from the Creator/creature distinction.
The incomprehensibility of God, therefore, lies at the basis of all proper thought respecting God. For the incomprehensibility of God is the correlate of His specific divinity. It is a correlate of His Godhood. There is ineffable mystery in God’s being, perfections, counsel, and will; and the recognition of this belongs to that reverence which is the soul of godliness. He dwells in light that is inaccessible, full of glory, and the clouds of darkness around about Him and His footsteps are not known. We cannot, by searching, find out God, the Almighty and the Perfect, so that, if this sense of mystery does not condition our thinking about God, it is because we are not governed by the profound apprehension of His majesty, an apprehension which is a reflection, in us, of His incomprehensibility and greatness. – John Murray [1898-1975], “Class Lectures in Systematic Theology,” as recorded by a student.
From: Systematic Theology by Morton H. Smith; 2 volumes (Greenville: Greenville Seminary Press, 1994), 1:105-106.