The Bible says: “The Lord Jesus Christ, on the night when He was betrayed, took bread, and when He had given thanks, He broke it, and said, ‘This is my body which is given for you. Do this in remembrance of me.’ In the same way also He took the cup after supper, saying, ‘This cup is the New Testament in my blood. Do this, as often as you drink it, in remembrance of me’” (I Corinthians 11:23-25; see also Matthew 26: 26-28, Mark 14: 22-24, and Luke 22: 19-20).
Luther explains: “What is the Sacrament of the Altar? It is the true body and blood of our Lord Jesus Christ under the bread and wine, instituted by Christ Himself for us Christians to eat and to drink.”
The question of Holy Communion (or the Lord’s Supper) divides Lutherans from other Protestants, even as it divided Martin Luther and Ulrich Zwingli during the course of the Reformation, keeping them from cooperating in their resistance to Rome. When Zwingli said that the bread represents the body of Christ and the wine represents his blood, Luther pointed to the words of the Bible and insisted, “’Is’ means ‘is’!”
Lutherans do not believe that the bread changes into Christ’s body or that the wine changes into Christ’s blood. They believe that Christ’s body is present with the bread and that his blood is present with the wine. The Real Presence of Christ in the Sacrament can be compared to the mystery of Christ’s two natures. As Jesus is completely God and completely human at the same time, so the bread in the Sacrament is completely bread and still completely Christ’s body; the wine is completely wine and still completely Christ’s blood.
Jesus instituted this Sacrament during a Passover dinner. In the Passover dinner, God’s people remembered the lamb that was killed in Egypt, its blood painted on their houses, so they would be spared death and rescued from slavery. John the Baptist identified Jesus as “the Lamb of God who takes away the sin of the world.” Part of the Passover meal was bread made without yeast, a picture of a life without sin. Jesus took that bread and said, “This is my body, given for you.” He took the cup of thanksgiving (the third of four cups served during the Passover meal, the one after supper) and said, “This cup is the New Testament in my blood.” Holy Communion replaces the Passover meal from which it was taken. The Sacrament is celebrated, not once a year like the Passover meal, but often when God’s people gather in the name of Jesus.
Because Jesus is human, he can give us his true body and his true blood. Because Jesus is God, he can keep on giving and never run out. When he appears in glory, he will be missing none of his body and none of his blood, even after feeding his body and blood to his people over many centuries. Yet the body and blood from his crucifixion are truly present whenever his Sacrament is observed. Even unbelievers who mistakenly eat and drink the Sacrament receive his body and his blood, but because they do not believe, they encounter a Judge rather than a Savior.
Human flesh is not kosher; it is not among the meats permitted in the Law of Moses for God’s people to eat. Even animal blood is forbidden; meat is not kosher until all the blood has been removed. Why, then, does Jesus give Christians his body to eat and his blood to drink? He does so because of the New Testament, which unites Christians with Christ in a special way. The metaphor of eating and drinking appears in many parts of the Bible to describe a believer’s relationship with God. In Holy Communion, the metaphor becomes reality, for as Luther said, “’Is means ‘is’!”