51 I myself am the living bread that has come down from heaven. 52 If anyone eats of this bread, he shall live for ever. And now, what is this bread which I am to give? It is my flesh, given for the life of the world.
54 Whereupon Jesus said to them, Believe me when I tell you this; you can have no life in yourselves, unless you eat the flesh of the Son of Man, and drink his blood. 55 The man who eats my flesh and drinks my blood enjoys eternal life, and I will raise him up at the last day. 56 My flesh is real food, my blood is real drink. 57 He who eats my flesh, and drinks my blood, lives continually in me, and I in him. 58 As I live because of the Father, the living Father who has sent me, so he who eats me will live, in his turn, because of me.
You need to read the whole chapter to get the whole context of what Jesus is talking about. Yes, that little section does look like Jesus is talking about a physical “eating” of his flesh, but you only get that by ignoring earlier verses, later verses and the fact that Jesus was foreshadowing communion, which is patterned after the Passover/Seder meal (which is also a REMEMBERANCE).
As a side note, this event is taking place around the Passover, so those following him understood more of what he was proclaiming because the bread in the Passover meal symbolized God.
Earlier in John 6, you read where Jesus references a number of times that those who BELIEVE on Him will have everlasting life. (29,35,40,47) However those who were questioning Jesus were seeking more physical miracles (like what he had done earlier in the chapter) so that their bellies could be filled. He keeps telling them that a physical bread, like manna that their ancestors had eaten, was a miracle like they were seeking, but that physical bread doesn’t save. He points that out that their ancestors ate manna and are dead (6:49).
Jesus wraps up the discussion with those who kept wanting a physical meal, by telling them that he was speaking of something spiritual.
John 6:63 “It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, [they] are spirit, and [they] are life.”
So, you see, when you look at the WHOLE chapter and the context and what the seder meal was (a rememberance of God saving Israel from the slavery of Egypt) you can see that what Jesus wants is for us to believe in Him (which requires faith and is “spirit”). He most certainly wasn’t telling these people that they needed to physically eat Jesus’s flesh and physically drink his blood.
Like I responded to someone else, the Catholic church builds doctrines off of a few verses taken out of context with the whole of scripture. This is wrong and it misleads millions of people.