"Counter-missionaries" (traditional Jews and/or converts who attempt to "prove" that Yeshua is NOT the Messiah and that the New Testament is a farce) will often use the following scripture to show "Jesus" can't be real because God would never demand that you eat His flesh or drink His blood - something that supposedly suggests he is a "vampire."
Let's put this outrageously ridiculous MISUNDERSTOOD scripture into its proper context with the help of footnotes from Andrew Gabriel Roth's Aramaic English New Testament:
John 6:53 And Y'shua said to them, Amen, amen I say to you, that unless you eat the body of the Son of man and drink his blood, you have no life in Qnoma. 54. And he who eats from my body and drinks from my blood has life that is everlasting, and I will raise him up on the last day. 55. For truly my body is food and truly my blood is drink. 56. He who eats my body and drinks my blood abides in me and I in him.
57. As the Living Father has sent me, and I live because of the Father, and whoever eats of me he also will live because of me. 58. This is the Bread that has descended from Heaven. It is not as manna your forefathers ate and died. He who eats this Bread will live forever! 59. He said these things while he taught in the assembly in Capurnakhum. 60. And many who heard it of his disciples said, "This saying is hard! Who is able to do it?"
61. But Y'shua knew in himself that his disciples were argueing about this, and he said to them, This offends you! 62. What if, therefore, you see the Son of man ascending to the place that he was before? 63. It is the Spirit that makes alive; the body does not profit anything. The words that I speak with you are spirit and are life. (Aramaic English New Testament)
Qnoma, usually translated here as "you", "self", or "yourselves", but literally means "Underlying substance." The body/blood imagery is metaphoric. Y'shua, of course, knows very well that it is an abomination to drink any kind of blood, let alone human blood (Leviticus 17:11). Consuming human flesh is also an abomination that is strictly prohibited. Rabbis even suggest that part of the reason swine's flesh is forbidden is because it resembles human skin.
There are two underlying parts: Part 1 recalls the imagery of Ezekiel 3:1-15 where the prophet actually ate a Torah scroll; the imagery symbolizing the prophet being sustained by and proclaiming Torah, which is the essence of what Y'shua is teaching. Y'shua's example and teaching are to be part of our innermost being, literally taken in and ingested into our hearts.
This imagery is also seen in Mark 7:19 which distinguishes between physical food and spiritual (heart) "food", and Jeremiah 31:33 which speaks of writing Torah upon the heart.
Part 2, is the life which Y'shua refers to; it is not physicality, as "self", but the core essence of being, literally of the neshama, (spirit of man).
"He who eats this Bread will live forever!" is clear evidence that opposes the "communion" model of mainstream Christian institutions. Nothing is being eaten while Y'shua is making this statement; he had just levied a rebuke for their desire of physical rather than spiritual "bread." It is Faith in Y'shua as Mashiyach which causes a person to "eat the flesh and drink the blood."
The "wafer" (transubstitution) is a Pagan adulteration against Y'shua's teaching. Y'shua observed Torah to perfection; his perfect atoning sacrifice would be remembered specifically on the Moedim (YHWH's feasts) as the Word of YHWH instructs.
As the "body does not profit anything," then neither can ingesting a wafer that symbolizes the body! Sin is violation of Torah. The absolution of sin begins with Teshuva (turning to YHWH). Faith in Mashiyach is evidence that the Ruach haKodesh has begun to write Torah upon the heart. Obedience to Torah as the Word of YHWH is the process of Sanctification, which is the setting apart of YHWH's people unto Himself, from all manner of worldliness and false religion. No volume of wafer-ism or canned prayer in or about Mashiyach will provide an acceptable substitute to being born into the Image of Elohim!