The Most Holy Eucharist is the greatest of all the Sacraments and stands at the very center of Catholic life. Because this mystery is so sacred, the Church has always insisted on careful and precise language when describing what occurs during the Holy Sacrifice of the Mass. When incorrect terms are used, they can unintentionally distort the Church’s teaching about the Real Presence of Our Lord in the Blessed Sacrament.
One common error is the belief that after the Consecration the bread and wine remain together with Christ’s Body and Blood. This idea is known as consubstantiation, a theory historically associated with Lutheranism. According to this view, Christ becomes present alongside the bread and wine, which continue to exist after the words of Consecration.
The Catholic Church rejects this explanation.
The Church teaches instead that at the moment of Consecration a complete and miraculous change takes place. This change is called Transubstantiation. By the power of Christ’s words spoken by the priest, the entire substance of the bread and wine is changed into the Body and Blood of Jesus Christ.
The Council of Trent, solemnly defining this doctrine, declared:
“Because Christ our Redeemer said that it was truly His Body that He was offering under the species of bread, it has always been the conviction of the Church of God… that by the consecration of the bread and wine there takes place a conversion of the whole substance of the bread into the substance of the Body of Christ our Lord, and of the whole substance of the wine into the substance of His Blood. This conversion is appropriately and properly called Transubstantiation by the holy Catholic Church.” (Council of Trent, Session XIII, Chapter IV)
After this change occurs, the bread and wine no longer remain. Only their accidents—that is, their outward appearances such as taste, color, and quantity—continue to exist. The underlying reality has been completely transformed into Christ Himself.
St. Thomas Aquinas explains this mystery with remarkable clarity:
“In this sacrament the whole substance of the bread is changed into the Body of Christ, and the whole substance of the wine into the Blood of Christ. Hence this change is not like natural changes, but is entirely supernatural, and effected by God’s power alone.” (Summa Theologiae, III, q.75, a.4)
For this reason Catholics must be careful when speaking about the Eucharist. It is not correct to say that Jesus becomes bread or wine. Rather, the opposite is true: the bread and wine cease to be what they were and become the Body and Blood of Christ.
Under the appearances of bread and wine, the faithful receive the true Body, Blood, Soul, and Divinity of Our Lord Jesus Christ. The same Savior who was born in Bethlehem, who offered Himself on Calvary, and who rose gloriously from the dead is made present upon the altar at every Mass.
Because this Sacrament is so profound, the Church has always guarded its language carefully. Using the correct terms—especially the doctrine of Transubstantiation—helps preserve the truth handed down from the Apostles: that in the Most Holy Eucharist, Christ Himself is truly present.
