Barth, CD I/2, p. 748-749:
If we consider what men are doing in the Church, ourselves or others, it is only by a crude self-deception that we can come to the conclusion that the Word of God is really being preached there. And when we have grown tired of this self-deception, if we still consider men in the Church, we shall arrive at the diametrically opposite but no less arbitrary conclusion, that the Word of God is not being preached in the Church...
What has to happen in order that the proclamation of the church may be the Word of God, and that men in the Church may really proclaim the Word of God, has already happened, as, generally speaking, everything that has to happen in order that the Church may live as the Church of God has already happened. Provision has been made that in the Church men may again and again believe and hope and love, that in it the name of God may be constantly invoked in thankful prayer, that in it the disciples of Jesus may ever and again suffer, and that in it brother may find brother and receive his help.
All that has been provided. No presupposition is required from us. We are not even asked whether we see it all performed and fulfilled by ourselves or others. Our business can only be that of accepting as something which has happened for us and to us that which has already been performed and fulfilled in Jesus Christ in respect of the whole life of the Church. It is always in this acceptance that the Church lives its life as created by Jesus Christ and rooted in him.
The same is true in relation to the proclamation of the Word of God, which is only one of the functions of the Church. It can only be a question of accepting what has already been created and founded in Jesus Christ. It is not we who have to care for the truth and validity of the identification of proclamation in the Church with the Word of God. We have to accept that it is so and allow it to be true.
Because Jesus Christ is risen, because God's revelation and testimonies are therefore given to the Church, it receives and holds His commission, which means that it has Himself in its midst as the Lord of its speaking, the Lord who in and through its speaking bears witness to Himself. Humanly speaking, it is a stark impossibility which stares us in the face - that men should speak what God speaks; but it is one which in Jesus Christ is already overcome. At the hands of those for whom it was in fact an impossibility, it brought as a blasphemer to the cross the One for whom it was not an impossibility, in order that it might be revealed in His resurrection as the new possibility for man, to be imparted by Him to His prophets and apostles and to be conveyed by their witness to the Church.