Can you explain transubstantiation to me in a way that I can understand? Every time I ask I'm given "the church says so" or told to read John 6:26-end but nothing in the scripture that I've read gives me any reason to think it was meant to be literal. Perhaps it's just because of the translation I have, I use NLT, but nothing I've read leads me to believe that was Jesus's intention in saying that. "Jesus said so" is a good enough reason for me to believe it but I struggle to see that he said it.
You’re right of course that not everything Jesus said can be taken literally. We do not believe that Jesus is literally a vine, or that we are literally called to become branches! There are two major clues, however, that in the case of Jesus’ assertion in John 6, “I am the bread of life”, a literal interpretation is the correct one.
The first is a shift in wording in the Greek text that is not reflected in English translations (though good study Bibles will mention it in footnotes). In verses 51 and 53, when Jesus says “I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world” and “Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you”, the Greek verb translated as “eat” is phago. But in verse 54, when Jesus reiterates “Whoever eats my flesh and drinks my blood has eternal life, and I will raise him on the last day”, the verb being translated as “eat” is now trogo, which is the word used to describe animal eating rather than human consumption. This deliberate choice of words implies a literal meaning.
Secondly, we have to look at the context. Elsewhere in scripture, when Jesus uses a metaphor and it is taken literally, scripture offers straightforward clarification of his true meaning. See John 2:19-22:
Jesus answered and said to them, “Destroy this temple and in three days I will raise it up.” The Jews said, “This temple has been under construction for forty-six years, and you will raise it up in three days?” But he was speaking about the temple of his body. Therefore, when he was raised from the dead, his disciples remembered that he had said this, and they came to believe the scripture and the word Jesus had spoken.
Here, John’s clarification is explicit and incontrovertible. There is no plausible way to argue that Jesus was actually speaking about Herod’s temple in verse 19. The Evangelist has specifically told us that this saying is a metaphor.
In John 6, the Jews to whom Jesus is speaking again take his words literally: “Is this not Jesus, the son of Joseph? Do we not know his father and mother? Then how can he say, ‘I have come down from heaven’?” (v. 42), “How can this man give us his flesh to eat?” (v. 52). But this time, no such clarification is offered. After his initial statement in verse 34, “I am the bread of life, whoever comes to me will never hunger, and whoever believes in me will never thirst”, Jesus reiterates seven times that it is necessary to eat his flesh in order to be saved (v. 48-50, 51, 53, 54, 55, 56, and 57-58), but neither he nor John ever offers an alternate interpretation of these sayings. Even when “many of his disciples returned to their former way of life and no longer accompanied him” because of this teaching (v. 66), no correction of their literal understanding is given.
The most commonly cited objection to this is John 6:63: “It is the spirit that gives life, while the flesh is of no avail. The words I have spoken to you are spirit and life.” But unlike the clarification about the temple in John 2, other interpretations of this verse are possible, and if Jesus is truly speaking of his own flesh here, and it is truly “of no avail”, then the entire Incarnation is meaningless - a conclusion clearly contradicted by scripture. Furthermore, the second part of this verse, “The words I have spoken to you are spirit and life”, reinforces everything Jesus has just said identifying himself with the bread of life by reminding us that his words are the revelation of the Spirit. Catholics therefore interpret verse 63 as an admonition that the doctrine of the Eucharist must be understood as something supernatural rather than natural; indeed, it is only by supernatural means that this man can give us his actual flesh to eat.
While John 6 is the most comprehensive scriptural basis for the doctrine of the Real Presence, the notion of Jesus giving us his flesh to eat is reinforced elsewhere in scripture. The Last Supper accounts in the other gospels (Matthew 26:26-28, Mark 14:22-24, Luke 22:19-20) are the source of the actual words of consecration said by the priest. St. Paul reiterates this account in 1 Corinthians 11:23-26, then goes on to say in verse 27: “Therefore whoever eats the bread or drinks the cup of the Lord unworthily will have to answer for the body and blood of the Lord.“ This is a rather strong condemnation if the Eucharist is merely a symbol, but a logical one if it is truly the body and blood of Christ.
Additionally, while not substantial proofs, many other biblical images fall into place and make more sense if the doctrine of the Real Presence is true. Jesus is the Lamb of God (John 1:29), the paschal lamb which has been sacrificed (1 Cor 5:7); we eat his flesh just as the Israelites ate the flesh of the paschal lamb in Egypt (Exodus 12:8). Jesus is the Word of God (John 1:1-5, 14), and we are told that man does not live by bread alone, but by every word that comes forth from the mouth of God (Deuteronomy 8:3, Matthew 4:4). The Church is the Bride of Christ (see Ephesians 5:21-32, Revelation 21:2,9-10), and the bride and groom are not merely united in spirit but “become one flesh” (Genesis 2:24, Matthew 19:5, Mark 10:7-8, Ephesians 5:31). The full meaning of all these teachings is only revealed by the bodily presence of Jesus Christ in the Blessed Sacrament.