Does John 6 Speak about the Lord's Supper?
When Jesus instituted the Lord's Supper, he said, "This [bread] is my body, which is given for you. Do this in remembrance of me" (Luke 22:19) and, "This cup that is poured out for you is the new covenant in my blood" (22:20). And so the bread and cup (or wine) represent his body and blood, which he gives as a sacrifice to inaugurate "the new covenant." In John 6, Jesus feeds five-thousand. Later in that chapter, he underscores the reality that the sign of the feeding points towards. He says, "Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever feeds on my flesh and drinks my blood has eternal life, and I will raise him up on the last day" (John 6:53–54). Do Jesus' words here refer to the Lord's Supper? After all, he offers his body and blood for eternal life here much like he does in Luke 22. Not quite. The difference is that Jesus offers the communication of his flesh in John 6 while he institutes the Lord's Supper in Luke 22.
Communication of the Flesh and the Lord's Supper
Everything that we see in the world points to an unseen reality, and that reality is God. When Jesus instituted the Lord's Supper, it was never meant to point to itself, as if the bread and wine literally saved. Instead, these two symbols point to the realities that Jesus himself specified: his death and shed blood for the new covenant. In John 6, Jesus offers the reality not the sign. John Calvin explains, "for this discourse does not relate to the Lord’s Supper, but to the uninterrupted communication of the flesh of Christ, which we obtain apart from the use of the Lord’s Supper" (Calvin, Comments on John 6:53).
What Is This Communication?
Communication of his flesh means union with Christ or abiding in him. Jesus explains, "Whoever feeds on my flesh and drinks my blood abides in me, and I in him" (John 6:56). So Jesus offers a mutual abiding where he becomes one with a believer. And this union gives life: the forgiveness of sins, the promise of immortality, and communion with God. How does this come about theologically? Calvin explains, "for as the eternal Word of God is the fountain of life, (John 1:4,) so his flesh, as a channel, conveys to us that life which dwells intrinsically, as we say, in his Divinity. And in this sense it is called life-giving, because it conveys to us that life which it borrows for us from another quarter" (Comm. on John 6:51). Put simply, by uniting to the humanity of Christ we partake of the divine life.
What Does the Lord's Table Do Then?
Christ's offer of abiding in him requires a real experience. And part of this fellowship with Christ occurs during the Lord's Supper. Calvin explains,
I say, therefore, that in the mystery of the Supper, Christ is truly shown to us through the symbols of bread and wine, his very body and blood, in which he has fulfilled all obedience to obtain righteousness for us. Why? First, that we may grow into one body with him; secondly, having been made partakers of his substance, that we may also feel his power in partaking of all his benefits. (John Calvin, Institutes, 4.17.11, 1372)
Note his emphasis on feeling "his power." Union with Christ and partaking of the "mystery of the Supper" through "the symbols" draws us closer to Christ, allowing us to experience his power. Note further the language of "mystery" and "symbols." Mysteries or symbols point to spiritual realities. So the Lord's Supper is a visible symbol that points to an unseen reality, and that reality is: (1) our union with him as "we may grow into one body with him" and (2) our partaking of divinity and experience of his power.
John 6
John 6 does relate to the Lord's Supper, but not because Jesus somehow instituted it in John 6. Rather, Jesus teaches on the reality of abiding in him to which the Lord's Supper points. Calvin explains, "I acknowledge that there is nothing said here that is not figuratively represented, and actually bestowed on believers, in the Lord’s Supper; and Christ even intended that the holy Supper should be, as it were, a seal and confirmation of this sermon" (Comm. on John 6:54). In other words, Jesus teaches on the realities that the Lord's Supper celebrate. And while Luke 22 and 1 Corinthians 11 importantly define and expand on the meaning of the Lord's Supper, we should not forget John 6. It is here where the Lord himself peels back the curtain, as it were, to show us the realities that the symbols of the bread and the wine point. And that reality is Christ abiding with us so that we can share in the divine and immortal life of God.