- Dietrich Bonhoeffer, The Cost of Discipleship, pp. 86-88
"In baptism we have the once-for-all and conscious entry and reception, manifested in the sign of purification, of the individual man into membership of the people of those who are called by God in free grace to be His witnesses, to participate in the work of His witness. And in the Lord's Supper we have the repeated and conscious unification of this people, manifested in the sign of common eating and drinking, in new seeking and reception of the free grace which it constantly needs and is constantly given in its work of witness. There is more to be said concerning baptism and the Lord's Supper. But it certainly has to be said concerning them that they are significatory actions in which people, instead of being merely alongside or even apart, both come and are together. They are thus actions which establish fellowship.
In baptism and the Lord's Supper an invisible action of God -- the fellowship of the Father and the Son in the Holy Ghost, the fellowship of God and man in Jesus Christ, the fellowship of Jesus Christ the Head with His body and its members, and finally the fellowship of God with the world created by Him and reconciled to Him -- is the prototype, the meaning and the power of the visible and significatory action of the community and therefore of the unification of persons therein attested. But on this basis and as likenesses of this original, baptism and the Lord's Supper are not empty signs. On the contrary, they are full of meaning and power. They are thus the simplest, and yet in their very simplicity the most eloquent, elements in the witness which the community owes to the world, namely, the witness of peace on earth among the people in whom God is well-pleased."
- Karl Barth, The Doctrine of Reconciliation IV/3, pp. 901