“I have no taste for corruptible food nor for the pleasures of this life. I desire the bread of God, which is the flesh of Jesus Christ, who was of the seed of David; and for drink I desire His blood, which is love incorruptible.” St. Ignatius of Antioch, “Epistle to the Romans,” c. 105 A.D.
“Heretics abstain from the Eucharist and from prayer, because they do not confess that the Eucharist is the Flesh of our Savior Jesus Christ.” St. Ignatius of Antioch, “Epistle to the Smyrneans,” c. 105 A.D.
“Not as common bread nor common drink do we receive these; but as we have been taught, the food which has been made into the Eucharist by the Eucharistic prayer set down by Him, and by the change of which our blood and flesh is nourished, is both the Flesh and Blood of that incarnated Jesus.” St. Justin Martyr, “First Apology,” c. 150 A.D.
“If the Lord were from other than the Father (and thus capable of performing miracles), how could He rightly take bread, which is of the same creation as our own, and confess it to be His Body and affirm that the mixture in the cup is His Blood? When, therefore, the mixed cup (wine and water) and the baked bread receives the Word of God and becomes the Eucharist, the Body of Christ, and from these the substance of our flesh is increased and supported, how can they say that the flesh is not capable of receiving the gift of God, which is nourished by the Body and Blood of the Lord, and is in fact a member of Him?” St. Irenaeus, “Against Heresies,” 189 A.D.
“He (St. Paul) threatens, moreover, the stubborn and forward and denounces them, saying ‘Whosoever eats the bread or drinks the cup of the Lord unworthily is guilty of the Body and Blood of the Lord’ (1 Corinthians 11:27). All these warnings being scorned and condemned (lapsed Christians will often take Communion) before their sin is expiated, before confession has been made of their crime, before their conscience has been purged by sacrifice and by the hand of the priest, before the offense of an angry and threatening Lord has been appeased, (and so) violence is done to His Body and Blood; and they sin now against their Lord more with their hand and mouth than when they denied the Lord.” St. Cyprian of Carthage, “The Lapsed,” 251 A.D.
“He Himself, therefore, having declared and said of the Bread, ‘This is My Body,’ who will dare any longer to doubt? And when He Himself has affirmed and said, ‘This is My Blood,’ who can ever hesitate and say It is not His Blood? Do not, therefore, regard the bread and wine as simply that, for they are, according to the Master’s declaration, the Body and Blood of Christ. Even though the senses suggest to you the other, let faith make firm. Do not judge in this matter by taste, but be fully assured by faith, not doubting that you have been deemed worthy of the Body and Blood of Christ.” St. Cyril of Jerusalem, “Mystagogic,” c. 350 A.D.
“The bread and the wine of the Eucharist before the holy invocation of the adorable Trinity were simple bread and wine, but the invocation having been made, the bread becomes the Body of Christ and the wine the Blood of Christ.” St. Cyril of Jerusalem, “Catechetical Lectures,” 350 A.D.
“Perhaps you may be saying: ‘I see something else; how can you assure me that I am receiving the Body of Christ?’ It but remains for us to prove it. And how many are the examples we might use! Christ is in that Sacrament, because It is the Body of Christ.” St. Ambrose, “The Mysteries,” 390 A.D.