‘Revelation means sacrament’. For God to reveal himself, this revelation must be disclosed in creaturely objectivity, adapted to our creaturely existence and knowledge. The theological concept of sacrament is thus bound up in the structure and nature of God’s revelation. Thus, there is ambiguity from the perspective of the human person – the objectification of divine revelation is not a predication of the creaturely mind – and a provisional aspect to revelation – the final Word of revelation encompasses the ‘end of history’ as well as its significance. This means that there is an eschatological tension between the revelation of God in its historical form and its ultimate reality. This is true both of revelation and sacrament as a sign of revelation.
1. The life, death and resurrection of Jesus Christ as the primary sacrament
Jesus Christ is the mysterion through which all sacramental ‘mystery’ is mediated and objectively confirmed (1 Tim 3:16).
In the New Testament mysterion denotes an event in the world of time and space which is directly initiated and brought to pass by God alone, so that in distinction from all other events it is basically a mystery to human cognition in respect of its origin and possibility. If it discloses itself to man, this will not be from without, but only from within, through itself and therefore once again only through God’s revelation … Faith as a human action is nowhere called (in Scripture) a mystery, nor is Christian obedience, nor love, nor hope, nor the existence and function of the ecclesia, nor its proclamation of the Gospel, nor its tradition as such, nor baptism, nor the Lord’s Supper.
The human nature of Jesus is the sacramental reality of revelation on the ground of the hypostatic union between the divine and human in the one person. There is attestation, or witness of God to humans and humans to God, in this primary event which is determinative of all secondary occurrences of the Christ event.
For, in the light of the attestation which occurred through the man Jesus, we find the attestation of God wherever it is the attestation of that occurrence. That the eternal Word as such became flesh is a unique occurrence. It happened only once. It is not therefore the starting point for a general concept of Incarnation. But its attestation through the existence of the man Jesus is a beginning of which there are continuations; a sacramental continuity stretches backwards into the existence of the people of Israel, whose Messiah He is, and forwards into the existence of the apostolate and the Church founded on the apostolate. The humanity of Jesus Christ as such is the first sacrament, the foundation of everything that God instituted and used in His revelation … And, as this first sacrament, the humanity of Jesus Christ is at the same time the basic reality and substance of the highest possibility of the creature as such.
2. The true mysterion is located in the single event of the incarnate presence of God in Jesus Christ
Baptism and the Supper are regarded in the New Testament as two aspects of the one event. There is, therefore, properly speaking, one sacrament, of which Baptism and the Supper are correlated expressions.
The language that the New Testament uses about Baptism is interchangeable with that it uses concerning the Supper (Cf. Mark 10:38f.; 1 Cor 10:1ff.; 12:12‑13). Thus, the relation between Baptism and the Supper is bound up in the Word of God as Incarnate, inscripturated, and proclaimed. This locates the objective reality of the sacraments in the presence of Christ both as an event within salvation history and as the Lord of the Church. There is a primary objectivity through Christ to which both the objective (physical) and subjective (personal) nature of the sacraments are bound.
Here it is important to see that the true mysterion is located in the primary objectivity – the Incarnation – and not in the secondary objectivity, the physical aspects of the sacrament. In the sacrament, undergirded by the Word of God and attended by the Spirit of Christ, the sacramental action of the Church itself takes place, through which the mysteries of the Kingdom concerning Jesus Christ are made known. The original presentation of God to humans and humans to God becomes a re‑presentation in the sacramental life of the church.
 Barth, CD II/1, 52.
 Barth, CD IV/4, 108‑9.
 Karl Barth, Church Dogmatics Il/2, (eds G. W. Bromiley and T. F. Torrance; trans. G. W. Bromiley; Edinburgh: T&T Clark, 1957), 54.