I think if you look closely at John 6, the religious folks were MOST offended by Jesus claims to be the Son of God. Cannibalism and drinking blood were never a serious consideration. One of God's first laws for Noah forbid this, as the antediluvian antics were fresh in everyone's mind. (Genesis 9:3-5)
John 5:17-18 (KJV) 17 But Jesus answered them, My Father worketh hitherto, and I work. 18 Therefore the Jews sought the more to kill him, because he not only had broken the sabbath, but said also that God was his Father, making himself equal with God.
Everything Jesus did was offensive to the religious. None more so than when Jesus said God was his Father. Read John 6 and you will see this was a big reason for the departure and murmuring at the Capernaum Synagogue.
John 5:24 (KJV) 24 Verily, verily, I say unto you,
He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
Hear the Word, and believe. Its the religious that make things complicated, not God.
Having established the core message in John to this point, now we look at John 6 and the context.
What did the crowd say? Were they really outraged about the figurative language? Consider the text again.
John 6:28-29 (KJV) 28 Then said they unto him, What shall we do, that we might work the works of God? 29 Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent.
Note what is required - that you believe in him. And this was after Jesus had told them they were just looking for more free food after the feeding the 5,000 miracle.
John 6:30-33 (KJV) 30 They said therefore unto him, What sign shewest thou then,
that we may see, and believe thee? what dost thou work? 31 Our fathers did eat manna in the desert; as it is written, He gave them bread from heaven to eat. 32 Then Jesus said unto them, Verily, verily, I say unto you, Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven. 33 For the bread of God is he which cometh down from heaven, and giveth life unto the world.
The religious folk were demanding a sign. They referenced Moses/Manna. Jesus provides a contrast - the Father gives the true bread which gives LIFE, not just sustenance.
John 6:34-35 (KJV) 34 Then said they unto him, Lord, evermore give us this bread. 35 And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and
he that believeth on me shall never thirst.
There seems to be a breakthrough, so Jesus provides the key - faith in him.
John 6:36-42 (KJV) 36 But I said unto you,
That ye also have seen me, and believe not. 37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out. 38 For I came down from heaven, not to do mine own will, but the will of him that sent me. 39 And this is the Father's will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day. 40
And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day. 41 The Jews then murmured at him, because he said, I am the bread which came down from heaven. 42 And they said, Is not this Jesus, the son of Joseph, whose father and mother we know? how is it then that he saith, I came down from heaven?
Nothing stirred the pot with the religious more than Jesus claiming to be God's Son. Note the Jews murmured and complained about Jesus whose parents they knew, saying he came from Heaven. For the religious, the heresy hunters of that era, blasphemy was far worse than cannibalism or drinking blood.
John 6:43-52 (KJV) 43 Jesus therefore answered and said unto them, Murmur not among yourselves. 44 No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day. 45 It is written in the prophets, And they shall be all taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto me. 46 Not that any man hath seen the Father, save he which is of God, he hath seen the Father. 47
Verily, verily, I say unto you, He that believeth on me hath everlasting life. 48 I am that bread of life. 49 Your fathers did eat manna in the wilderness, and are dead. 50 This is the bread which cometh down from heaven, that a man may eat thereof, and not die. 51 I am the living bread which came down from heaven: if any man eat of this bread, he shall live for ever: and the bread that I will give is my flesh, which I will give for the life of the world. 52 The Jews therefore strove among themselves, saying, How can this man give us his flesh to eat?
Verse 44 is very important. The god of this world has blinded the minds of them which believe not. (2 Corinthians 4:4) And the natural man receiveth not the things of the Spirit of God. (1 Corinthians 2:14) These folks are not prepared to receive the Gospel, religion is blinding them. They did not really know God, or His Word, therefore, they did not recognize Jesus, the Living Word.
Look at v.47 - He that believeth on me hath everlasting life. This is a spiritual message, not physical, and they do not understand. Note v.51 - the bread that I will give is my flesh, which I will give for the life of the world. Jesus will give FOR the life of the world, NOT TO the world. Look what the Jews say in response - How can this man give us his flesh to eat?
Notice who introduced cannibalism into the discussion?
From John 1 forward, this Gospel continually reminds you that Jesus and the Word are the same. They cannot be separated. It is Truth. It is a common Hebrew expression to CONSUME God's Word, as seen in: Deuteronomy 8:3, Psalm 19:9-10, 119:103, 131, Jeremiah 15:16, Ezekiel 2:8-10, 3:1-4, Matthew 4:4, Hebrews 6:4-5, 1 Peter 2:2, Revelation 10:9-10. SO... in light of that, the figurative language makes perfect sense, especially when you note that Jesus said he will give his flesh, it was the religious that took that to mean cannibalism.
John 6:53-60 (KJV) 53 Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you. 54 Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day. 55 For my flesh is meat indeed, and my blood is drink indeed. 56 He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him. 57 As the living Father hath sent me, and I live by the Father: so he that eateth me, even he shall live by me. 58 This is that bread which came down from heaven: not as your fathers did eat manna, and are dead: he that eateth of this bread shall live for ever. 59 These things said he in the synagogue, as he taught in Capernaum. 60 Many therefore of his disciples, when they had heard this, said, This is an hard saying; who can hear it?
And now, Jesus provides the knockout punch, a 'hard saying' in a final attempt at a breakthrough. As with Nicodemus, it would be appropriate for Jesus to say here, John 3:12 - "If I have told you earthly things, and ye believe not, how shall ye believe if I tell you of heavenly things?" These folks were trapped in their own religious ideas.
NOBODY, past, present, or future, would assume Jesus was going to saw off his arm and hand it to the Capernaum Jews to chew on. Nor would anyone assume they would be drinking his blood. As they said, it was a 'hard saying', just like pluck out your eyes, I am the vine, or cut off your foot, or I am the door, or unless your righteousness surpasses the righteousness of the Pharisees you will never enter the Kingdom of Heaven.
These were religious folks, zealous of the Law. Neither cannibalism or drinking blood would ever be considered. If they were so offended, why didn't they leave after this hard saying? Instead, there was something coming that would be far more offensive.
There is contrast here between physical food (manna) and spiritual food (faith in Jesus - the Word made flesh - John 1). Eating bread and wine does nothing for your spirit or mind - the ones that ate the manna all died. Jesus obeyed God's Word. He only spoke God's Word. His very life was based precisely on doing God's Will, which is His Word. For Believers, the Word saves and builds faith (Romans 10:17, Galatians 3:5, 1 Thessalonians 2:13), the Word renews your mind (Romans 12:2, Ephesians 5:25-27, Colossians 3:10, 2 Timothy 3:15-18).
John 6:61-66 (KJV) 61 When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you? 62 What and if ye shall see the Son of man ascend up where he was before? 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. 64
But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who should betray him. 65 And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of
my Father. 66 From that time many of his disciples went back, and walked no more with him.
Verse 63 makes it clear that Jesus is not referring to physical eating or drinking. He is talking about faith in him, the Living Word. And look at v.65, Jesus is repeating the same thing from v.43-44 that originally set the religious folks off. And it was from THAT time they they began to leave.
John 6:67-71 (KJV) 67 Then said Jesus unto the twelve, Will ye also go away? 68 Then Simon Peter answered him, Lord, to whom shall we go? thou hast the words of eternal life. 69 And we believe and are sure that thou art that Christ, the Son of the living God. 70 Jesus answered them, Have not I chosen you twelve, and one of you is a devil? 71 He spake of Judas Iscariot the son of Simon: for he it was that should betray him, being one of the twelve.
Then Jesus turns to his disciples - did they have ears to hear? And look at Peter's response, he doesn't even mention eating flesh or drinking blood, apparently Peter understood the expression and the Revelation found in Jesus' words - why can't the religious today? When responding to the question if they would depart, Peter says, "You have the
words of eternal life." --- THE WORD - faith is in God's Word! Its so simple a child can understand.
Why weren't the rest scandalized by the use of such figurative language? They had ears to hear, and a love for God. They could receive some Truth. They weren't offended by Jesus' claims to be from Heaven, or that God was his Father. This was early in the ministry, so the disciples had no knowledge of the coming Last Supper, and cannibalism and drinking blood were contrary to the Law. They only had their knowledge of God's Word from the OT, Revelation from God, and what Jesus had taught until that time.
Why do you suppose that the Communion account, is not included in John's Gospel?
John, looking back, would have commented further if this event were related to the Last Supper, but he did not. His Gospel was written well after Pauls' revelation to the Church was in circulation, some say as late as the 90s AD. This was the last Gospel written, and by far the most powerful of the four IMHO. John also gives the most comprehensive account of the last words of Jesus during the same time as the Last Supper, filling 4 chapters with a powerful revelation of Jesus, the Holy Spirit, and the Father, as well as their relationship with Believers. And yet not a peep about eating flesh and drinking blood in those 4 chapters.
I don't know the answer, but I find it a very interesting omission. Had the Holy Spirit wanted the account included, it certainly would have been.