Barth begins his treatment of the doctrine of God with a chapter entitled “The Knowledge of God.” The chapter has three sections, the first being “The Fulfilment of the Knowledge of God” itself comprised of two sub-sections.
In the first sub-section, “Man before God,” Barth provides a description of how the knowledge of God occurs—from a human perspective. He begins by assuming that the knowledge of God is a reality in the church: “In the Church of Jesus Christ men speak about God and men have to hear about God” (3). That this knowledge occurs in the church is a result of the gracious gift of God by which God has made himself known and makes himself known. True confidence must begin here—with the actuality rather than the possibility of the knowledge of God. We do not ask whether God might be known but rather how far God is or might be known (5). This is an epistemological claim: the knowledge of God occurs only in its occurrence—where God is actually known, where the fulfilment of this knowledge takes place. There is no neutral position or standpoint whereby one might test, explore, or prove the knowledge of God without having already heard the Word of God and been brought within the circle of the knowledge of God.
God is a unique Object, known only as he gives himself as an object of human knowledge. God is not one amongst others, not one in a series, nor an abstract postulate such as a ‘Supreme Being’ or ‘First Cause.’ God—the true and living God—is not a god one might identify or choose for oneself; such an entity could never be God. For Barth, this principle is self-evident for there is, in fact, only one God—the self-existent One who exists eternally as Father, Son, and Holy Spirit. To have knowledge of this God is to have the knowledge of God. To have knowledge of some other god or concept or being is not the knowledge of God.
The knowledge of God with which we are here concerned takes place, not in a free choice, but with a very definite constraint. It stands or falls with its one definite object. . . . Because it is bound to God’s Word given to the Church, the knowledge of God with which we are here concerned is bound to the God who in His Word gives Himself to the Church to be known as God. Bound in this way it is the true knowledge of the true God (7).
This, therefore, is the ‘very definite constraint’ with which the church is ‘bound,’ that is, God is known only as he gives himself to be known in his Word. “Any escape out of the constraint of the Word of God means crossing over to the false gods and no-gods” (7).
Confident Christian speech about God—good apologetics—must begin under the discipline of this constraint. Nor is it the case that we choose the constraint: we rather find ourselves constrained by the Word that has come to us. “We can only come from the real and original constraint by the Word; we cannot come to it” (9). Barth cites Psalm 127:1-2 (Except the Lord build the house, their labour is but lost that build it), giving it epistemological force. “Good apologetics is distinguished from bad by its responsibility to these words” (9).
Barth’s first point, then, is that the knowledge of God is mediated knowledge; there is no unbound, non-objective, or immediate knowledge of God. We know God only through the mediacy of his Word in the church where he gives himself to be known as an object of human knowledge.
If God gives Himself to man to be known in the revelation of His Word through the Holy Spirit, it means that He enters into the relationship of object to man the subject. In His revelation he is considered and conceived by men. Man knows God in that he stands before God. But this always means: in that God becomes, is and remains to him Another, One who is distinct from himself, One who meets him. Nor is this objectivity of God neturalised by the fact that God makes man His own through the Holy Spirit in order to give Himself to be owned by him (9-10).
In making himself an object for human knowledge, God remains nevertheless “the primarily acting Subject of all real knowledge of God, so that the self-knowledge of God is the real and primary essence of all knowledge of God” (10).
Several observations about Barth’s point can now be made: first, any true human knowledge of God is always a gift of divine grace. Barth takes it as axiomatic that genuine knowledge of God is beyond human capacity. God is not an object of human observation or enquiry in a manner similar to other phenomena. Rather, God makes himself an object of human knowledge by giving himself to be known by humanity as this object. Unless God does this, humankind cannot know God. That God has done this is an act of divine condescension and grace, an act of the Holy Spirit who makes the human subject capable of the knowledge of God (10).
Second, the knowledge of God is a personal and relational knowledge: God comes to the human person as Another, meeting them as this Other, and giving himself to be known by them. The human subject finds themselves encountered by God—a transcendent Subject who makes himself an object for their apprehension—and so come to know Him and not merely about him. While God knows himself perfectly and immediately, they know him only mediately and contingently yet still truly. The knowledge they have is an aspect of God’s own self-knowledge.
Third, as noted, this knowledge of God is also a mediated knowledge, a knowledge given to us by his Word in the church. Only by starting out and staying on this path can one attain the knowledge the God. God can only be known where God has given himself to be known: other paths lead to false gods and no-gods, gods of human invention and so not at all the knowledge of God. Barth warns against mystical attempts to ascend to God immediately:
This ascendere and transcendere means abandoning, or at any rate wanting to abandon, the place where God encounters man in His revelation and where He gives Himself to be heard and seen by man. . . . If we really soar up into these heights, and really reduce all concepts, images, words and signs to silence, and really think we can enter into the idipsum [the ‘self-same’; the thing itself], it simply means that we wilfully hurry past God, who descends in His revelation into this world of ours. Instead of finding Him where He Himself has sought us—namely, in his objectivity—we seek Him where He is not to be found, since He on His side seeks us in His Word (11).