1. The mode of sacramental relation reflects the mode of hypostatic union between humanity and deity in Christ
Christ as the objective union of human and divine in his own person is also the objective presence of God to humans and humans to God. All forms and theories with regard to this ‘presence’ are relative to this objective ‘presence’ of God in Christ. Again, we must say that the mysterion is located in the Incarnate One, not in the mechanical or supernatural relation between physical element and spiritual grace.
The medieval doctrine of transubstantiation was confirmed in 1215 as official dogma. This formulation of the relation of Christ to the elements takes the is, ‘this is my body’, with the strictest literalism. Philosophically, this miracle was explained by Thomas Aquinas on the basis of the Aristotelian distinction between the accidents of a thing (its perceptible characteristics, such as taste, texture), and the essence or substance of a thing (the true reality of a thing). Thus, in the miracle of transubstantiation, when the prayer of the Priest invokes the presence of Christ into the elements, the substance of bread is transformed into the substance of flesh, while the accidental qualities of bread remain. Thus Christ is assumed to be actually present as real substance in the bread and wine, leading to the adoration of the elements as well as a propitiatory immolation of Christ in a ‘sacrifice’.
The Reformers agreed on the rejection of this notion of ‘real presence’ and sacrifice based on the doctrine of transubstantiation, with Luther holding that Christ is truly present ‘under and with the elements,’ in such a way that the humanity of Christ becomes capable of omnipresence wherever the Lord’s Supper is held due to the doctrine of the ubiquity (i.e. omnipresence) of the human nature of Jesus. This is explained in Lutheran theology by the concept of communicatio idiomatum – where the properties belonging to one of the natures of Christ is fully incorporated into the other. Some have termed this Lutheran view, ‘consubstantiation.’ Luther wrote, ‘What is the sacrament of the Altar? It is the true Body and Blood of our Lord Jesus Christ, under the bread and wine, given unto us Christians to eat and to drink, as it was instituted by Christ Himself.’
Calvin, on the other hand, while denying ‘real presence’ in terms of substance, spoke in terms of a ‘spiritual’ presence of Christ in the form of the assembled company of believers who receive the elements:
… he has, through the hand of his only-begotten Son, given to his church another sacrament, that is, a spiritual banquet, wherein Christ attests himself to be the life-giving bread, upon which our souls feed unto true and blessed immortality … (B)read and wine … represent for us the invisible food that we receive from the flesh and blood of Christ. For as in baptism, God, regenerating us, engrafts us into the society of his church and makes us his own by adoption, so we have said, that he discharges the function of a provident householder in continually supplying to us the food to sustain and preserve us in that life into which he has begotten us by his Word. Now Christ is the only food of our soul, and therefore our Heavenly Father invites us to Christ, that, refreshed by partaking of him, we may repeatedly gather strength until we shall have reached heavenly immortality.
The view of Zwingli tended to be more of a memorial supper focussing on the historical event of Christ’s death and resurrection, with his presence ‘in the Spirit,’ so that the sacramental elements themselves were totally symbolic, possessing no qualities of ‘presence.’ So, ‘The presence of Christ’ in the Lord’s Supper is understood by Zwingli in an ‘idealistic’ fashion, so to speak, by Luther in a tangible‑‘objective’ fashion, by Melanchton in an actual fashion, and by Calvin in a ‘spiritual fashion.’
Karl Barth adds an important warning: ‘From the standpoint of the community itself, of the company assembled round the table of the Lord, what takes place will always be highly problematical. Yet’, he goes on, ‘in spite of this it is a fellowship of the Lord’s Supper, united by Him both with Him and also, because with Him, in itself; communio sanctorum as a fellowship of the sure and certain hope of eternal life.’
3. The eschatological union between creature and Creator grounds the Church both in a history as well as in a future
The Lord’s Supper reaches back into the event of Christ’s death – ‘On the night on which he was betrayed.’ It also reaches forward into the future – ‘Until he comes’ (1 Cor 11:23, 26). ‘Through the Eucharist the Church becomes, so to speak, the great arch that spans history, supported by only two pillars, the Cross which stands on this side of time, and the coming of Christ in power which stands at the end of history.’
David Watson suggests that the Lord’s Supper causes the Christian to look in four directions:
i. to look back by remembering God’s mercy when he delivered his people from bondage; and to the Cross, the great event of deliverance from sin;
ii. to look in by purifying oneself from everything evil;
iii. to look around by including one’s entire household as well as the stranger;iv. to look forward by anticipating the coming of Christ and the completion of the Messianic age.
 Cf. G. Bromiley, ‘Transubstantiation’, in Evangelical Dictionary of Theology (ed. W. A. Elwell; Grand Rapids: Baker, 1991), 1108. Also Berkouwer, Sacraments, 219ff.
 Martin Luther, ‘Small Catechism, Book of Concord’, in Joseph Stump, An Explanation of Luther’s Small Catechism (Whitefish: Kessinger, 2004), 21.
 John Calvin, Institutes of the Christian Religion, IV.17.1. (ed. J. T. McNeill; trans. F. L. Battles; Philadelphia: The Westminster Press, 1977), 2:1360f.
 Weber, Foundations, 632.
 Barth, CD IV/2, 704.
 Torrance, Conflict, 171.
 David Watson, I Believe in the Church (London: Hodder & Stoughton, 1999), 237‑241.