What is a name really? And what is the point of speaking of a name of God? First, we can say that there is a fundamental difference between purpose of a concept and that of a name. The concept tries to perceive the nature of the thing as it is in itself. The name, on the other hand, does not ask after the nature of the thing as it exists independently of me; it is concerned to make the thing nameable, that is “invocable”; to establish a relation to it. Here too the name should certainly fit the thing, but to the end that it comes into relation to me and in this way becomes accessible to me.
Let us take an example: if I know of someone that he falls under the concept “man”, this is still not enough to enable me to establish a relation to him. Only the name makes him nameable; through the name the other enters into the structure, so to speak, of my fellow-humanity; through the name I can call him. Thus the name signifies and effects the social incorporation, the inclusion in the structure of social relations. Anyone who is still regarded only as a number is excluded from the structure of fellow-humanity. But the name establishes the relation of fellow-humanity. It gives to a being the “invocability” from which co-existence with the namer arises. This will probably make clear what Old Testament faith means when it speaks of a name of God.
The aim is different from that of the philosopher seeking the concept of the highest Being. The concept is a product of thinking that wants to know what that highest Being is like in itself. Not so the name. When God names himself after the self-understanding of faith he is not so much expressing his inner nature as making himself nameable; he is handing himself over to men in such a way that he can be called upon by them. And by doing this he enters into co-existence with them, he puts himself within their reach, he is “there” for them.
Here too is the angle from which it would seem to become clear what it means when John presents the Lord Jesus Christ as the real, living name of God. In him is fulfilled what a mere name could never in the end fulfill. In him the meaning of the discussion of the name of God has reached its goal, and so too has that which was always menat and intended by the idea of the name of God.
From: Introduction to Christianity, pp. 91-92