In The Faith of Millions—a book certified by the Roman Catholic Church to be “free of doctrinal and moral error”—Catholic priest John O’Brien explains what happens during the Mass:
When the priest pronounces the tremendous words of consecration, he reaches up into the heavens, brings Christ down from His throne, and places Him upon our altar to be offered up again as the Victim for the sins of man. It is a power greater than that of monarchs and emperors: it is greater than that of saints and angels, greater than that of Seraphim and Cherubim. Indeed it is greater even than the power of the Virgin Mary. While the Blessed Virgin was the human agency by which Christ became incarnate a single time, the priest brings Christ down from heaven, and renders Him present on our altar as the eternal Victim for the sins of man—not once but a thousand times! The priest speaks and lo! Christ, the eternal and omnipotent God, bows His head in humble obedience to the priest’s command.
The supposed ability to wield such supernatural power over almighty God is one of the priesthood’s most blasphemous acts. As O’Brien describes it, the priestly office is a position of immense, even ultimate power, as the priest yanks Christ out of His eternal kingdom and hurls Him once again onto the sacrificial altar.
The repeated sacrificial process is called transubstantiation, wherein the bread and wine transform into the literal body and blood of Christ. It may sound cannibalistic and creepy, but they argue that it’s what the Bible actually teaches:
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 yourselves. He who eats My flesh and drinks My blood has eternal life, and I will raise him up on the last day. For My flesh is true food, and My blood is true drink. He who eats My flesh and drinks My blood abides in Me, and I in him. (John 6:53–56)
But is that really what Jesus meant by those graphic words? Was He truly prescribing the repeated and violent sacrifice of His physical body? Is that what Christ intended when He instituted Communion?
The simple answer is, No.
https://www.gty.org/blogs/B160212/are-we-called-to-literally-eat-christs-flesh-and-drink-his-blood