The Lord's Supper

Communion, also called the Lord's Supper in many Protestant denominations, or the Eucharist in the more liturgical churches, is one of the two sacraments specifically instituted by Christ in the New Testament, the other being Baptism.

Jesus instituted this ordinance with his disciples at the Last Passover on the eve of his arrest. This event is specifically recorded in Luke 22:14-23 with Jesus saying "do this in remembrance of me." (22:19) The remembrance is to be of Christ's person and work, specifically his sacrificial death on the cross. This ordinance is a sign of God's grace whereby:
Jesus gave his body and blood for our sins (Luke 22:19-20),
he entered into a covenant with us (Luke 22:20, 1 Cor 11:25), and
he joined us into one body, his church (1 Cor 10:16).

The Westminster Confession defines it in this manner: "Our Lord Jesus, in the night wherein He was betrayed, instituted the sacrament of His body and blood, called the Lord's Supper, to be observed in His Church, unto the end of the world, for the perpetual remembrance of the sacrifice of Himself in His death; the sealing all benefits thereof unto true believers, their spiritual nourishment and growth in Him, their further engagement in and to all duties which they owe unto Him; and, to be a bond and pledge of their communion with Him, and with each other, as members of His mystical body." (WCF, 29.1).

Historical positions:

Luther
Luther's position (particularly as developed by subsequent Lutheranism) is referred to as a "real physical presence" of Christ in the elements. The bread is still bread, but it is also truly the body of Christ. And while the wine does not lose its "wine-ness", it is very much the actual blood of Christ. Luther found Jesus' words "This is my body" (Hoc est corpus meum) as a mandate for such an understanding. This view is often conflated with consubstantiation, which is a philosophical rather than a theological view.


Consubstantiation is a philosophical theory that, like the competing theory of transubstantiation, attempts to describe the nature of the Christian Eucharist in concrete metaphysical terms. It holds that during the sacrament the fundamental substance of the body and blood of Christ are present alongside the substance of the bread and wine, which remain present.


Transubstantiation differs from consubstantiation in that it postulates that, through consecration by the priest, one set of substances (bread and wine) is exchanged for another (the Body and Blood of Christ) or that, according to some, the reality of the bread and wine become the reality of the body and blood of Christ. The substance of the bread and wine do not remain, but their accidents (superficial properties like appearance and taste) remain.


Consubstantiation is commonly—though erroneously—associated with the teachings of Martin Luther and Philipp Melanchthon. Lutheran teachings reject any attempt to explain philosophically the means by which Christ is present in the Eucharist. Luther did teach that the body and blood of Christ are present "in, with, and under the forms" of bread and wine, and present-day Lutherans hold to this statement while disagreeing about its exact meaning. Some Lutherans do use the term "consubstantiation" to refer to this belief, but the theology intended is not the same as the philosophical theory described above. Luther illustrated his belief about the Eucharist "by the analogy of the iron put into the fire whereby both fire and iron are united in the red-hot iron and yet each continues unchanged," 1 a concept which he called sacramental union. Consubstantiation is affirmed by a minority of Christians, including some Eastern Orthodox churches.


The Roman Catholic doctrine that the bread and wine, used in the Lord's Supper or Eucharist, actually become the literal body and blood of Christ at the "consecration" by the ordained priest. This is based on a super-literal reading of Christ's words, "This is my body, which is broken for you" (1 Corinthians 11:24, KJV); and on His Johannine discourse, "Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you" (John 6:53, KJV).
Roman Catholics believe that "by the words, Do this in commemoration of me (Luke 22:19; 1 Corinthians 11:24), Christ made the apostles priests. Moreover, He decreed that they and other priests should offer His Body and Blood." [1] This doctrine should not be confused with the Lutheran doctrine of Consubstantiation.

Zwingli
The position associated with Zwingli is sometimes referred to as the memorialist position, or the "real absence" view. That might be somewhat misleading: everyone agrees that the Supper is to be a memorial of Christ's death and resurrection. The question is whether it is more than that. While most modern evangelicals suggest, at least in practice, that it is not - Zwingli does seem to have some place for the notion of a spiritual feeding of Christ. Ultimately though, both he and Oecolampadius rejected Luther's position at Marburg because they saw it as a threat to the validity of Christ's resurrection and ascension - if Christ was physically resurrected in body, that body cannot be in two places at once (ie. at the right hand of the Father and in the bread/wine). To argue that it could, as Luther did, seemed to challenge the physical nature of Christ's resurrection.

Calvin
Calvin's understanding would emerge after that of Luther and Zwingli, but attempted to offer somewhat of a middle ground. He drew heavily on Augustinian definitions of the nature of sacraments, arguing that the Eucharist was a visible sign of an invisible reality. So that while the bread is nothing more than bread, it signifies and presents to us a spiritual reality that takes place - a spiritual feeding on Christ by which believers are nourished. Calvin sought to answer the question posed by Zwingli (on how Christ could be in two places at once) by proposing that at the Supper, Christians are taken into communion with Christ in heaven by the Holy Spirit. So Christ is exclusively present in body at the right hand of the Father. If that is confusing to you, don't worry - Calvin himself admitted a level of mystery, saying that he would rather experience the reality of the Supper than understand it.