John 6:56, “Whoever feeds on My flesh and drinks My blood abides in Me, and I in him.”
Martin Luther, and many Lutherans with him, argue this is not a foreshadow of the Lord’s Supper, but is rather Jesus speaking on a “spiritual eating” of faith. How Calvinistic. It is not an either/or question but a both/and question. If this were no foreshadow, Jesus would not use such literal language. Of course, He did not mean, “Bite into my arm right now,” but pointed to the feast that is to come. It is a bit early in the narrative of John’s gospel for this foreshadow, certainly, but so what?
It also makes sense that John would have these words for the Lord’s Supper since his gospel lacks the event of the institution of the Lord’s Supper. Considering that John’s gospel is a much later gospel than the others, it is highly possible that John was writing to a people fully aware of the Lord’s Supper. If we Lutherans are going to take the word “is” in the words of institution seriously, then we ought to also take Jesus’ words here seriously, “Whoever feeds on My flesh and drinks My blood.”
This is a both/and issue: Jesus is speaking of the actual eating of His flesh and the drinking of His blood in the Lord’s Supper He will institute, the table of whom only those who have faith in Christ approach. Therefore, if you partake of Jesus’ body and blood and believe He is truly present in the elements just as He stated He is, then you know without a doubt that you abide in Him and He in you. It is as sure as the sweet taste of the wine on your lips and the bread going down your gullet. Cling to this truth, and all doubt will wash away with Jesus’ blood you have swallowed.