Catholic 101: Transubstantiation

by | Apr 6, 2023 | Catholic 101, Sacraments

I remember when I was confronted by the Eucharist. I was around 17 years old. It wasn’t a single moment exactly, but a long period of steady thinking, especially while I was at Mass or in Adoration. Try as I might during this time, I found it quite difficult to pray. I was stuck, just thinking.  This article will detail that thinking and where it led me, which as you might expect, was to full belief in the Real Presence of Jesus Christ in the Eucharist.

I grew up Catholic, baptized into the Church just a month and two days after my birthday. What others found peculiar about Catholic practice and doctrine were never peculiar to me. They were just what we did, just part of life, just how we were. I don’t remember when I first learned the term “transubstantiation.” It seems like I’ve always known it, really. Assuredly, when I did learn it, it didn’t add anything. It would’ve been just a word for something I already believed, namely, that the bread and wine at Mass become Jesus’ flesh and blood. I don’t think there’s been a time in my life when I didn’t believe that, though I have had my difficulties.

Those difficulties began when I was in middle school and especially high school, as the content of my faith was suddenly scrutinized, engaged intellectually and with argument. My teachers brought me the difficulties as they passed down to me the Church’s teachings. They were not content with simple answers nor justifying articles of faith through platitudes or half-baked ideas. They were exceedingly faithful to their task, so they presented reasonable objections to what the Church believed. If either side got the more generous treatment, it was the other side. Such a method showed the seriousness of the Church’s teachings, successfully inculcating in me and my fellow students a similar lesson which St. Augustine learned in the midst of his conversion, that “the Church…did not entertain infantile nonsense.”1

When it came to transubstantiation, the instruction was, from what I recall, mostly metaphysical. Every year between the ages of 13 and 18 I learned, at various levels of detail and depth, St. Thomas Aquinas’ Aristotelian distinction between substances and accidents. This is because “transubstantiation” refers to a change in which the substance of a thing—what it really is—changes, while its physical characteristics do not. Of course, this sort of change only occurs in the Eucharist, which, though it appears to remain bread and wine throughout the Mass, nevertheless truly becomes the flesh and blood of Jesus. My teachers tried to show me that such a change was not impossible, and I think they were successful. After all, a genuine distinction between what can be touched/seen/smelled (accidents) and what lies beneath (substances) means that such a change can occur, for it implies that, being different things, both can act independently of the other.

I came to understand through my teachers that St. Thomas’ approach is just one way of defending the possibility of such a change. His way is not what is exclusively meant by the word “transubstantiation,” although his is the explanation that has become most common (and there is probably good reason for that). Nor is it assumed by the Church’s Magisterium, which uses the word species rather than accidents.2 The only thing that is necessarily implied by the word “transubstantiation” is that there is a change that occurs which is real and substantial, yet which is simultaneously unobservable in every way. That is no small claim, it seems to me, especially when you consider that you have never observed such a change elsewhere. Moreover, it is not exactly a normal idea that the end result of this never-observed change is the flesh and blood of the God-Man, Jesus Christ himself.

I soon realized how counterintuitive this teaching was, and it unnerved me. My teachers had taught me that the Eucharist was the “source and summit of Christian life,” so I understood that basically everything rode on this rather strange teaching. 3 I also realized that, even though I found St. Thomas’ metaphysics reasonable and compelling, it was not a sufficient reason for my belief in transubstantiation. Just because it is possible does not mean that it actually happens. In fact, not even St. Thomas saw it as the reason for his belief. He was merely defending something he had already accepted.

All of this brought me to a deep confrontation with the reality of the Eucharist and, therefore, the doctrine of transubstantiation. It pressed on my mind, on my whole self in fact, as I could not reasonably ignore the magnitude of the question. As I sat there thinking in Mass or in adoration, it occurred to me that there were only two options. Either the Church’s claim that bread and wine became the flesh and blood of Jesus was true or it was false; there were no other options. This cut straight to my heart, for I understood that there would be related consequences.

If the teaching was false, I could not think of a more compelling refutation of the Mass, the practice of Eucharistic devotion, and the very existence of the Catholic Church. If the source and summit were false, the whole faith would be nothing but idolatry and superstition. Since I desired to live coherently, I knew the falsity of the doctrine would demand something of me: a rejection of this teaching and the Church that professes it. If the Eucharist was not flesh and blood, then I knew that I would have to leave the Church.

If it was true, however, this too would demand something. It would mean that at every Mass and in every tabernacle in the world, there is the real and in some sense, tangible presence of Jesus Christ. Furthermore, it would mean that I consume his flesh, that he becomes, in a real way, one with me, and not only with me but with all who receive him. This would compel me to a greater love of all my fellow Catholics, who were themselves tabernacles. I could not think of a truth more awesome than this, and I knew that, if it were true, my whole life had to be informed by this one reality.

So I searched for a good reason for my belief, a good reason for the Church’s belief. Having been impressed by the arguments and eloquence of St. Thomas, I expected the Church to have a similarly rational reason for this teaching. When I learned why we believe this, I was indeed impressed, but for the opposite reason. It was not the eloquent presentation of some beautiful logic but the simple and humble offering of just a single reason: we believe this because Jesus said so. Pure trust in the word of the Lord—that compelled me.

And it was evident to me that Jesus did in fact say so. The Gospels of Matthew, Mark, and Luke all report that at the Last Supper, Jesus said, “This is my body…this is my blood” (Mt. 26:26-28; Mk. 14:22-24; Lk. 22:19-20). Additionally, Paul relates the same thing in his first letter to the Corinthians, that Jesus said about bread that it was his body and about wine that it was his blood (1 Cor. 11:23-25). Furthermore, John’s gospel records Jesus telling a crowd multiple times that they must eat his flesh and drink his blood because he is the bread of life (Jn. 6:22-59). 

I was also convinced that we were right to understand that Jesus meant just what he said exactly as he said it, for my teachers pointed me to the Fathers of the Church, who attest to our same belief. See St. Justin Martyr around 154 AD:

The food which has been made into the Eucharist by the Eucharistic prayer… is both the flesh and blood of that incarnated Jesus.

See St. Athanasius of Alexandria around 295 AD:

So long as the prayers of supplication and entreaties have not been made, there is only bread and wine. But after the great and wonderful prayers have been completed, then the bread is become the body, and the wine the blood, of our Lord Jesus Christ.

See St. Augustine around 414 AD:

That bread which you can see on the altar, sanctified by the word of God, is the body of Christ. That cup, or rather what the cup contains, sanctified by the word of God, is the blood of Christ.

I decided to believe in the words of Christ and to strive to live accordingly, and I still find myself confronted by the awesome reality of the Eucharist, particularly in moments when I forget just how bold and consequential this doctrine—this reality—really is. When I neglect my devotion to Jesus at Mass, when I am tempted to think that the Lord is far away, when I fail to love those with whom I worship, all of these are opportunities for conversion toward a deeper love for Christ whose flesh and blood is that Eucharist.

When I do find myself in this state of apathy toward the Eucharist, I recall to mind that either-or which cut to my heart years ago. Either this is true or it isn’t; there’s no getting around it. That usually shakes me awake and helps me reorder myself around this great gift. So, I offer it to you: what do you make of the Church’s teaching on the Eucharist? Let that question cut to your heart. Strive boldly to live the consequences of the answer you provide.

  1. St. Augustine in The Confessions, Book VI.
  2. Catechism of the Catholic Church (CCC) #1376; Paul VI, Mysterium Fidei, 46; John Paul II, Ecclesia de Eucharistia, 25.
  3. CCC #1324.