John 6v53
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.
Christ is using a metaphor. V 30 shows the Jews looking for a sign. It seems they were trying to impose this thinking on the Saviour, that He should show them a sign like Moses had done. There are warnings in Scripture against this. "A wicked and adulterous generation require a sign, etc" -- this is a fruit of the native unbelief and unwillingness to accept the word of the Lord which has already ben given. Yet, in this case, Christ does use the idea of a sign.
The Jews at this point could not understand the significance of His words. Now we have the full revelation of Calvary, we can and ought to understand this figurative language here. The manna Moses gave was not THE life-giving bread; it was a miracle and sign and proof that God spoke by Moses but not THE bread. Christ points to this by saying "My Father giveth you the true bread" (v32)
In v53 Christ is giving the application of the metaphor.
1. The verse teaches there must be a receiving of Him. This is as fundamental as the Father giving Him, and He giving Himself on Calvary. A man is not a Christian unless he believes that the Father sent the Son to redeem. Christ came to do the will of Him that sent him. What a will that was, what requirements were attached to it! O how essential it is. Christ's life is not just an example or pattern of behaviour, but He lived that he might give His flesh for the world, (men of evrry kind, not just Jews). He was giving His life, it was substitution, one in the place of another, Christ crucified. This was the commandment of the Father. Christ gave Himself as a ransom for many.
But, it's equally essential that they would eat. There's a receiving of His flesh and blood by faith. It's a spiritual receiving of the atonement.
2. The teaching is a distinguishing doctrine -- it discriminates between people.
3 These words are soul-humbling; it's a doctrine which offends or humbles.
4. It is a soul-satisfying doctrine. "My flesh is meat indeed". It is in proportion to their faith, that their soul gets satisfaction.