The Catholic Church maintains the real body and blood of Christ is present during communion. One of the texts they frequently use to support this claim is John 6, where Jesus says He is the "bread of life." We will examine the chapter in context to see what this passage teaches.
Verses 1 to 15: Jesus feeds 5,000 with bread and fish
Verses 16 to 24: Jesus walks on water and meets the disciples. The crowd realizes He's not there, and they go to Capernaum to search for Him.
Verse 25: They ask Jesus how He got there.
Key verse--->
Verse 26: They were looking for Him, not because of miracles, but because they ate and had their full.
Verse 27: "Do not work for food that spoils, but for food that endures to eternal life which the Son of Man will give you."
Verse 28: The crowd asks what they must do to do the works of God. Notice this is in response to Jesus telling them that they must work for food that endures to eternal life.
Verse 29: The answer to their question. The work of God is to believe in the one He has sent.
Verse 30: The crowd asks for a sign, like manna in the desert.
Verse 32, 35: Jesus is the true bread. He who comes to Him won't be hungry, He who believe won't be thirsty. Notice the parallel. Jesus is saying that the satisfaction of their hunger is belief in Him. This follows the comments about "food that endures to eternal life." What Jesus is saying here is that He is the food, and the manner in which you eat is belief. The eating is part of the metaphor. Bread is to Jesus as Eating is to Believing.
Verse 40: Everyone who believe will have eternal life and will be raised at the last day.
Verse 41: The crowd begins to grumble about the "bread" comment.
Verse 47: He who believes has eternal life.
Verse 48: Jesus is the bread of life.
Verse 51: He who eats this bread will live forever. Important Question: Is this talking about the Eucharist of the Lord's Supper? Does Catholic theology teach eternal life by eating the communion wafer? No they don't. Any old schmoe could walk into a service, receive communion, and have eternal life. That's what this verse teaches if it is about the Lord's Supper. Catholics want this passage to be about the Eucharist, but if we carry out their interpretation to its logical conclusion it contradicts Catholic theology.
We shouldn't miss the point here in verse 51. Verse 47 says those who believe have eternal life. Verse 51 says those who eat the bread of life will. But Jesus has already established the metaphor, which I have already shown from the text. This just continues that.
Jesus continues, "This bread is my flesh, which I will give for the life of the world."
Verse 54: "Whoever eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day." Notice the parallel between verse 54 and 40. Those who believe will be raised on the last day (v. 40). Those who eat and drink Jesus' flesh and blood in this verse will be raised on the last day.
This passage in no way, once we understand the context, supports the Catholic view of the Real Presence in the Lord's Supper. It isn't even talking about the Lord's supper. Jesus very clearly lays out the metaphor to interpret the passage. He even plainly equates believing on Him with eternal life. The context is that Jesus just fed the 5,000. Passover and the Lord's Supper are nowhere in view. We need a pretext to bring the Catholic view into the text. As we have seen, the Catholic view of the text would lead to a contradiction with other areas of Catholic theology (one could die with a mortal sin and go to hell, even if one eats the communion wafer). The Catholic interpretation is a clear example of bringing a pet dogma and stuffing it into a text. And here it doesn't fit.