"Jesus said to them, 'I am the bread of life…and the bread that I will give for the life of the world is my flesh…Very truly, I tell you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Those who eat my flesh and drink my blood have eternal life…for my flesh is true food and my blood is true drink. Those who eat my flesh and drink my blood abide in me, and I in them." - John 6:35-58
Notice the force of Jesus' words; you have to twist them around to not get a Eucharistic interpretation of this passage. Some Protestants point to John 6:63 where Jesus says, "It is the spirit that gives life; the flesh is useless. The words that I have spoken to you are spirit and life," for "proof" that Jesus was only speaking metaphorically. They also say that Jesus used many other metaphors about Himself (such as the light of the world, gate for the sheep, and the vine). First of all, to eat one's flesh and drink one's blood in Jewish culture at the time meant to injure someone (see Psalm 27:2, Ecclesiastes 4:5, Isaiah 9:20, 49:26, Micah 3:1-3), so if Jesus was speaking metaphorically, He would've been using a REALLY BAD metaphor. Now, the Jews did question Jesus and ask what He meant, and then John switched vocabulary. In John 6:54-58, the Greek word used for "eat," "trogo," means literally to "chew" or to "gnaw." The only other times it is used in the New Testament are in Matthew 24:38 and John 13:18, both referring to literal eating. Now, comparing this to Jesus' other metaphors is like mixing apples and oranges. We can see and understand how Jesus is like a light or a gate or a vine, but where is the connection between bread and His flesh? As I have shown, to eat one's flesh and drink one's blood meant to injure, so it would've been a bad metaphor. In John 6:63, Jesus is not contrasting a physical Eucharist with a symbolic one. To take this verse at face value, we would conclude that ALL flesh is bad, and we'd become Gnostics. Jesus was contrasting human things (flesh) with things from God (spirit), and the Eucharist and His words are from God.
"While they were eating, Jesus took a loaf of bread, and after blessing it he broke it, gave it to the disciples, and said, 'Take, eat; this is my body.' Then he took a cup, and after giving thanks he gave it to them, saying, 'Drink from it, all of you; for this is my blood of the covenant, which is poured out for the forgiveness of sins." - Matthew 26:26-28
Notice that Jesus says, "This IS my body," not "This REPRESENTS my body." Nothing in this passage gives the impression that Jesus is speaking symbolically, especially when compared to John 6:35-58. Also, the Eucharist is the fulfillment of the Jewish Passover, and Jesus is the Paschal Lamb. The Jews had to eat the lamb; they couldn't just eat little lamb-shaped wafers. Scott Hahn does an excellent job of explaining this in The Fourth Cup.
"The cup of blessing that we bless, is it not a sharing in the blood of Christ? The bread that we break, is it not a sharing in the body of Christ?" - 1 Corinthians 10:16
How much clearer could Paul have been? The Eucharist is Jesus' physical body and blood! Some Protestants will say that it is a sharing in the body of Christ because we are all members of the body of Christ, and the Eucharist unites us, so Paul didn't mean that the bread and wine change to Jesus' literal body and blood. However, Paul says that not only is the bread a sharing in the body of Christ, but the blood is a sharing in the blood of Christ! Where is the community of Christians described as the blood of Christ? It isn't. Paul meant that the bread and wine literally change into Jesus' body and blood.
"Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be answerable for the body and blood of the Lord. Examine yourselves, and only then eat of the bread and drink of the cup. For all who eat and drink without discerning the body, eat and drink judgment against themselves." - 1 Corinthians 11:27-29
Again, we see Paul affirming the real presence in the Eucharist. To be answerable for one's body and blood meant to be guilty of murder, and Paul says that we are answerable for Jesus' body and blood if we don't discern the body.
