Jesus does not divide himself. Nor does he multiply himself. Jesus is one. And he is fully present in the Eucharist under the appearances of bread and wine.
Note that appearances includes everything that is perceptible to the senses. Location, both temporal and physical, is also an appearance. Everyone receiving communion receives the one entire Jesus, yet Jesus is not multiplied or divided. The appearances are multiplied, Jesus is not.
I think you hit the nail on the head. It’s that we cannot perceive God with our own senses. When I tried using my own limited vocabulary to explain this concept/mystery to my friend, his words were “You’re being too mysterious about all this because you KNOW that the Real Presence contradicts the Hypostatic Union because Jesus cannot be in two places at once.”
However, now that I’ve meditated on this, read more, and asked God for wisdom and insight, I realize that the key to the misunderstanding is that Heaven is not located in “space”. It is wherever God is and being able to truly SEE him. I think in Protestantism the concepts of heaven, God the Father, Jesus, and the Holy Spirit and their unique roles and characteristics as part of the Godhead are significantly misunderstood.
Here’s the thing - Jesus doesn’t divide Himself when transubstantiation occurs. When we consume the Eucharist, we consume all of Jesus - body, blood, soul, and divinity. In other words, we consume both of Jesus’s natures - His human nature and His Divine Nature. Through the multiplication of the loaves, Jesus showed the Jewish people that He would feed everyone with Himself. But the multiplication of the loaves was just a prefiguration of the Eucharist. And we see this in the discussion that Jesus has with the Jewish people in the Gospel of John after the multiplication of the loaves. Jesus pretty much told them: “You’re impressed by this? This is nothing. I am going to feed all generations who believe in Me with Myself.” It wasn’t until the Last Supper that the Eucharist was instituted and Jesus freely gave Himself in His Body and Blood, Soul and Divinity. One might wonder how Jesus was able to give His disciples Himself to eat before the crucifixion. Quite simply, because Jesus knew that the Sacrifice of the Cross was going to transcend space and time. If the Sacrifice of the Cross was able to sanctify Mary at her conception, keeping her free from all sin (which is what the Church teaches), then Jesus would also be able institute the Eucharist with His full Body, Blood, Soul and Divinity before His Sacrifice was completed in the temporal realm.
Protestantism, especially my friend’s version of it, seems to put God in a box. One of the biggest eye-openers for me in the process of learning to “think like a Catholic” is that God is not limited and cannot be limited by man and man’s ability to perceive. It’s like Jesus told them in John 6, “the flesh is of no avail.” Our flesh cannot perceive this beautiful mystery of the Eucharist. It takes eyes of faith that are given to us by the Holy Spirit.
Council of Trent:
“And this faith has ever been in the Church of God, that, immediately after the consecration, the true Body of our Lord, and His true Blood, together with His soul and Divinity, are under the species of bread and wine; but the Body indeed under the species of bread, and the Blood under the species of wine, by the force of the words; but the body itself under the species of wine, and the blood under the species of bread, and the soul under both, by the force of that natural connection and concomitancy whereby the parts of Christ our Lord, who has now risen from the dead to die no more, are united together; and the Divinity, furthermore, on account of the admirable hypostatic union with His body and soul.”
So the hypostatic union is the reason that His Divinity is present with His humanity in the Eucharist.
I think my friend’s reasoning and understanding of the Catholic explanation of transubstantiation was more along the lines of “the humanity tags along with the Divinity because of hypostatic union” instead of vice versa. He was trying to say that Jesus’ humanity was limited in time and space because if He couldn’t be divided, how could He (Body, Blood, Soul and Divinity) be in two places at once, in heaven and in the Eucharists all around the world?
Honestly, at the point he asked the question, I didn’t know enough to be able to sufficiently answer it (and I’ll probably never be able to do so since it is a mystery in large part).
Your friend is thinking in terms of a “mortal” body like ours. She/we do not fully comprehend what capabilities our “immortal, glorified” bodies will have.
In heaven, our bodies will be fully subject to our soul/spirit. Thus, if Jesus desires & wills in His human soul (which is always in accord with His divinity) to be present **body, blood, soul **& divinity in many places simultaneously here on earth, then He will be. His body will be present wherever His human soul/spirit wills to be and is.
A quote by St Leo the Great, pope:
…their bodies will be transformed by a joyous resurrection and clothed in the glory of immortality. No longer opposed in any way to their spirits, their bodies will remain in perfect harmony and unity with the will of the soul. …
What a great quote! Yes, I believe you are correct, he is thinking of Jesus in terms of a mortal body limited in time and space. I don’t think he is seeing past that point to fully realize that our immortal, glorified bodies will be capable of doing. I also think this misunderstanding causes many Protestants to question the practice of praying through the saints.
). R.C. Sproul is a dangerous person. His misrepresentation of the Catholic faith in many aspects seeths with bitterness and anger and sadly, my friend thinks he’s brilliant. Sproul lost all credibility with me when I saw a video of him encouraging people to “gleen” and “mine the ore” of the riches of the early church fathers, who he described as Martin Luther, John Calvin, and Jonathan Edwards. He did also mention Augustine, but nothing about St. Ignatius of Antioch, St. Clement of Rome, St. Polycarp, St. Justin Martyr, etc. 
