adorer:
Does anyone know when this was first taught? Similarly, why do we have to have a priest to know we are consuming Jesus’ body and blood? Any information on this would be very helpful.
Here are some of the earliest teachings on the concept of Transubstantiation outside of John 6 and the Gospel accounts of the Last Supper:
St. Paul, writing about A.D. 56, said:
“The cup of blessing which we bless, is it not a participation in the blood of Christ? The bread which we break, is it not a participation in the body of Christ?” (1 Cor 10:16)
“Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord.” (1 Cor 11:27)
“For any one who eats and drinks without discerning the body eats and drinks judgment upon himself.” (1 Cor 11:29)
St. Ignatius of Antioch, writing about A.D. 107 in his Letter to the Smyrnaeans, said:
“They [Heretics] abstain from the Eucharist and from prayer, because they confess not the Eucharist to be the flesh of our Saviour Jesus Christ, which suffered for our sins, and which the Father, of His goodness, raised up again.”
St. Justin Martyr, writing about A.D. 155 in his First Apology, said:
“For not as common bread and common drink do we receive these; but…have we been taught…is the flesh and blood of that Jesus who was made flesh.”
St. Irenaeus of Lyon, writing about A.D. 180, in Against Heresies said:
“…the bread, …when it receives the invocation of God, is no longer common bread, but the Eucharist, consisting of two realities, earthly and heavenly.”
Jesus “has acknowledged the cup…as His own blood, from which He bedews our blood; and the bread…He has established as His own body, from which He gives increase to our bodies.”
“…the mingled cup [of wine] and the manufactured bread receives the Word of God, and the Eucharist of the blood and the body of Christ is made”