Jesus is truly present at every Mass.
How do we know Jesus is truly present at every Catholic Mass in the physical appearance of bread and wine? Why must we eat His Flesh and drink His Blood? Answer: Jesus tells us and then doubles down when His followers question the weirdness of it.
To wrap our heads around this, we must look to the gospels of Matthew, Mark, Luke, and John, and to the letters of St. Paul and the accounts of the early Church fathers.
John makes it very clear in Chapter 6 of his book, starting at Verse 25:
When they found him on the other side of the sea, they said to him, “Rabbi, when did you come here?”
Jesus answered them, “Truly, truly, I say to you, you seek me, not because you saw signs, but because you ate your fill of the loaves. Do not labor for the food which perishes, but for the food which endures to eternal life, which the Son of man will give to you; for on him has God the Father set his seal.” Then they said to him, “What must we do, to be doing the works of God?”
Jesus answered them, “This is the work of God, that you believe in him whom he has sent.” So they said to him, “Then what sign do you do, that we may see, and believe you? What work do you perform? Our fathers ate the manna in the wilderness; as it is written, ‘He gave them bread from heaven to eat.’”
Jesus then said to them, “Truly, truly, I say to you, it was not Moses who gave you the bread from heaven; my Father gives you the true bread from heaven. For the bread of God is that which comes down from heaven, and gives life to the world.” They said to him, “Lord, give us this bread always.”
Jesus said to them, “I am the bread of life; he who comes to me shall not hunger, and he who believes in me shall never thirst. But I said to you that you have seen me and yet do not believe. All that the Father gives me will come to me; and him who comes to me I will not cast out. For I have come down from heaven, not to do my own will, but the will of him who sent me; and this is the will of him who sent me, that I should lose nothing of all that he has given me, but raise it up at the last day. For this is the will of my Father, that every one who sees the Son and believes in him should have eternal life; and I will raise him up at the last day.” The Jews then murmured at him, because he said, “I am the bread which came down from heaven.” They said, “Is not this Jesus, the son of Joseph, whose father and mother we know? How does he now say, ‘I have come down from heaven’?”
Jesus answered them, “Do not murmur among yourselves. No one can come to me unless the Father who sent me draws him; and I will raise him up at the last day. It is written in the prophets, ‘And they shall all be taught by God.’ Every one who has heard and learned from the Father comes to me. Not that any one has seen the Father except him who is from God; he has seen the Father. Truly, truly, I say to you, he who believes has eternal life. I am the bread of life. Your fathers ate the manna in the wilderness, and they died. This is the bread which comes down from heaven, that a man may eat of it and not die. I am the living bread which came down from heaven; if any one eats of this bread, he will live for ever; and the bread which I shall give for the life of the world is my flesh.” The Jews then disputed among themselves, saying, “How can this man give us his flesh to eat?”
So Jesus said to them, “Truly, truly, I say to you, unless you eat the flesh of the Son of man and drink his blood, you have no life in you; he who eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. For my flesh is food indeed, and my blood is drink indeed. He who eats my flesh and drinks my blood abides in me, and I in him. As the living Father sent me, and I live because of the Father, so he who eats me will live because of me. This is the bread which came down from heaven, not such as the fathers ate and died; he who eats this bread will live for ever.” This he said in the synagogue, as he taught at Caper′na-um. Many of his disciples, when they heard it, said, “This is a hard saying; who can listen to it?”
But Jesus, knowing in himself that his disciples murmured at it, said to them, “Do you take offense at this? Then what if you were to see the Son of man ascending where he was before? It is the spirit that gives life, the flesh is of no avail; the words that I have spoken to you are spirit and life. But there are some of you that do not believe.”
After this many of his disciples drew back and no longer went about with him. Jesus said to the twelve, “Will you also go away?”
Simon Peter answered him, “Lord, to whom shall we go? You have the words of eternal life; and we have believed, and have come to know, that you are the Holy One of God.”
Wow, what an incredible chapter from John. Jesus makes it absolutely clear that if we want to live forever in the kingdom of God (aka Heaven), we must eat His Flesh and drink His Blood.
Many are skeptical that simple bread and wine can be offered at Mass to become truly the Body and Blood of Jesus, as were the disciples at the time who said, “This is a hard saying; who can listen to it?” We may even be tempted to think, “Oh, Jesus was talking symbolically.” But Jesus reiterates over and over that no, we must eat His literal flesh to have eternal life. He does that FIVE times.
Also, if Jesus was explaining to just simply think of him while eating the offered up bread and wine (consuming the flesh and blood in a symbolic way), the disciple would not have responded as that being a “hard saying”. It might be weird but not hard for them to accept that.
Jesus acknowledges them being critical of this teaching, but then points out who He is. This is critical because this isn’t some ordinary person teaching a really strange lesson, it is Jesus Christ who literally is God who created everything we see around us from nothing!
“It is the spirit that gives life, the flesh is of no avail” is a line that gets confusing for many Christians. This line does not refer to the Flesh of Jesus, but the flesh meaning fallen human nature. Fallen human nature is powerless to raise itself up because we need God’s grace. The spirit gives life, while fallen human nature is of no avail. Whenever Jesus talks about His Flesh, He refers to it as “my flesh”, not “the flesh”.
Some neat extra facts from scripture about the reality of the Eucharist:
Interestingly, in the ancient Greek text of this scripture, there are two words used that we have just translated as ‘eat’: phago (basic eating) and trogo (gnawing, crunching, or chewing). And the word used in this context of eating his flesh is trogo, a graphic and more literal way to demonstrate eating, instead of using the more basic word phago which could be used in a more symbolic sense.
Also interestingly, the verse where the disciples walk away after hearing about Jesus double down on the importance of eating and drinking His Body and Blood is John 6:66 (666, yikes, according to the Book of Revelation, this is the number of Satan).
Finally, as we learned from the Gospel of Luke, Jesus was born in a manger (a feeding trough). Jesus, the Bread of life, who we must eat to have eternal life was born in a feed trough. Coincidence?