From the Very Beginning
The same thing is true in our relationships. Whether consciously or subconsciously, we look for consistency in the lives of the people around us to determine if they are authentic and trustworthy. If someone constantly changes how they act, doesn’t follow through on commitments, gives us erratic advice, or treats us with respect one day and disrespect the next…we know they cannot be trusted.
This is no different when it comes to religious beliefs and institutions. Over the span of 2000 years, the Catholic Church has been remarkably consistent. And nowhere is that more evident in her unwavering commitment to the teaching that Jesus is truly present in the Eucharist.
From the very beginning, the Catholic Church has consistently and emphatically proclaimed is that in the Mass, the Eucharistic bread and wine truly become the body and blood of Jesus Christ.
Here is just a small sample of the teaching of the early Christians and Church Fathers on the Eucharist. They speak with one voice about the reality of the True Presence:
Acts 2:46–47 in 33 AD: “And day by day, attending the temple together and breaking bread in their homes, they partook of food with glad and generous hearts, praising God and having favor with all the people. And the Lord added to their number day by day those who were being saved.” (Acts 2:46-47)
Saint Paul in ~55 AD: “The cup of blessing which we bless, is it not a participation[e] in the blood of Christ? The bread which we break, is it not a participation[f] in the body of Christ? 17 Because there is one bread, we who are many are one body, for we all partake of the one bread.” (1 Corinthians 10:16-17)
St. Ignatius of Antioch in 107 AD: "They abstain from the Eucharist and from prayer because they do not confess that the Eucharist is the flesh of our Savior Jesus Christ, flesh which suffered for our sins and which that Father, in his goodness, raised up again." (Letter to the Smyrnaeans, Chapter 7)
Saint Justin Martyr in 148-155 AD: "This food we call the Eucharist…we have been taught that the food consecrated by the Word of prayer which comes from him, from which our flesh and blood are nourished by transformation, is the flesh and blood of that incarnate Jesus." (First Apology, Chapter 66)
Saint Ephrem in 350 AD: "Our Lord Jesus took in His hands what in the beginning was only bread; and He blessed it… and made it holy…One particle from its crumbs is able to sanctify thousands and thousands, and is sufficient to afford life to those who eat of it. Take, eat, entertaining no doubt of faith, because this is My Body…” (Homilies)
Saint Cyril of Jerusalem in 348-378 A.D.: “What seems bread is not bread, though bread by taste, but the Body of Christ; and that what seems wine is not wine, though the taste will have it so, but the Blood of Christ.” (Mystagogic Catechesis 4,1.)
Saint Gregory of Nyssa in 385: “Rightly then, do we believe that the bread consecrated by the word of God has been made over into the Body of God the Word.” (The Great Catechism, 37)
Saint Ambrose of Milan in 391 A.D.: "You perhaps say: 'My bread is usual.' But the bread is bread before the words of the sacraments; when consecration has been added, from bread it becomes the flesh of Christ. So let us confirm this, how it is possible that what is bread is the body of Christ. By what words, then, is the consecration and by whose expressions? By those of the Lord Jesus." (The Sacraments, Book 4, Ch.4:14)
Saint Augustine of Hippo in 400 A.D.: “That which is seen is the bread and the chalice; that which is believed is the Body and Blood of Christ. This is called the bread, not only because by the physical sense of taste it nourishes the body, but also because by faith it nourishes and strengthens the heart.” (Sermons, 227)