I believe in the doctrine of transubstantiation, but I’m hung up a little on exactly how John 6:63 fits into Catholic apologetics. Jesus has just told his crowd of followers that they must eat his flesh and drink his blood to have eternal life. Protestants say that verse 63 is where Jesus clarifies that he was speaking figuratively, not literally, because he says “it is the Spirit that gives life; the flesh is useless.”(NRSV) So I hunted down some Catholic commentary on this verse, but it would be helpful to hear it in someone’s own words.
Here’s what I’ve found…
From the Geneva Study Bible on crosswalk.com:
[font=Arial, Helvetica][size=2]6:63 14 It is the x spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, [they] are spirit, and [they] are life.
(14) The flesh of Christ therefore quickens us, because he that is man is God: and this mystery is only comprehended by faith, which is the gift of God, found only in the elect.
(x) Spirit, that is, that power which flows from the Godhead causes the flesh of Christ (which is oth[/size][/font][font=Arial, Helvetica][size=2]erwise nothing but flesh) both to live in itself and to give life to us.
[/size][/font]And under the topic Transubstantiation in the Catholic Encyclopedia at newadvent.org:The entire scene of the discourse and murmurings against it proves that the Zwinglian and Anglican interpretation of the passage, “It is the spirit that quickeneth”, etc., in the sense of a glossing over or retractation, is wholly inadmissible. For in spite of these words the Disciples severed their connection with Jesus, while the Twelve accepted with simple faith a mystery which as yet they did not understand. Nor did Christ say: “My flesh is spirit”, i.e. to be understood in a figurative sense, but: “My words are spirit and life”. There are two views regarding the sense in which this text is to be interpreted. Many of the Fathers declare that the true Flesh of Jesus (sarx) is not to be understood as separated from His Divinity (spiritus), and hence not in a cannibalistic sense, but as belonging entirely to the supernatural economy. The second and more scientific explanation asserts that in the Scriptural opposition of “flesh and blood” to “spirit”, the former always signifies carnal-mindedness, the latter mental perception illumined by faith, so that it was the intention of Jesus in this passage to give prominence to the fact that the sublime mystery of the Eucharist can be grasped in the light of supernatural faith alone, whereas it cannot be understood by the carnal-minded, who are weighed down under the burden of sin. Under such circumstances it is not to be wondered at that the Fathers and several Ecumenical councils (Ephesus, 431; Nicæa, 787) adopted the literal sense of the words, though it was not dogmatically defined (cf. Council of Trent, Sess. XXI, c. i).
The Geneva Study Bible notes sound totally contradictory, but I’m guessing that it’s just outdated wording or maybe not the best modernized translation.
Now, one Protestant perspective I read said that Jesus’ spiritual metaphor didn’t make sense to his followers because they were used to thinking in physical terms, but today’s Christians are sometimes confused by the metaphor because we are used to thinking in spiritual terms. I don’t agree with their conclusion, but I think there is something to the argument, especially since Protestants are groomed to see spiritual metaphors where Catholics see a literal truth.
By the way, it’s interesting to see that the New Living Translation of verse 63 tends to support transubstantiation. It reads, “It is the Spirit who gives eternal life. Human effort accomplishes nothing.”