St. Ignatius of Antioch
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. [Letter to the Romans 7 (c. A.D. 105)].
Take note of those who hold heterodox opinions on the grace of Jesus Christ, which have come to us, and see how contrary their opinions are to the mind of God. . . . 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 that suffered for our sins and that the Father, in his goodness, raised up again. They who deny the gift of God are perishing in their disputes [Letter to the Smyrnaeans 6–7 (c. A.D. 110)].
St. Justin Martyr
We call this food Eucharist, and no one else is permitted to partake of it, except one who believes our teaching to be true and who has been washed in the washing that is for the remission of sins and for regeneration [i.e., has received baptism] and is thereby living as Christ enjoined. For not as common bread nor common drink do we receive these; but since Jesus Christ our Savior was made incarnate by the word of God and had both flesh and blood for our salvation, so too, as we have been taught, the food that 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 nurtured, is both the flesh and the blood of that incarnated Jesus [First Apology 66 (c. A.D. 151)].
St. Irenaeus of Lyons
If the Lord were from other than the Father, 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? [Against Heresies 4:33:2 (c. A.D. 189)].
He has declared the cup, a part of creation, to be his own blood, from which he causes our blood to flow; and the bread, a part of creation, he has established as his own body, from which he gives increase to our bodies. When the mixed cup [wine and water] and the baked bread receive the Word of God and become 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 eternal life—flesh that is nourished by the body and blood of the Lord, and is in fact a member of him? [ibid., 5:2:2–3].
St. Clement of Alexandria
“Eat my flesh,” [Jesus] says, “and drink my blood.” The Lord supplies us with these intimate nutrients, he delivers over his flesh and pours out his blood, and nothing is lacking for the growth of his children [Instructor of Children 1:6 (c. A.D. 197)].
Tertullian of Carthage
[T]here is not a soul that can at all procure salvation, except it believe while it is in the flesh, so true is it that the flesh is the very condition on which salvation hinges. And since the soul is, in consequence of its salvation, chosen to the service of God, it is the flesh that actually renders it capable of such service. The flesh, indeed, is washed [in baptism], that the soul may be cleansed. . . . The flesh is shadowed with the imposition of hands [in confirmation], that the soul may be illuminated by the Spirit; the flesh feeds [in the Eucharist] on the body and blood of Christ, that the soul may fatten on its God [Resurrection of the Flesh 8 (c. A.D. 210)].
St. Cyril of Jerusalem
[A]s the bread and wine of the Eucharist before the invocation of the Trinity, which is holy and worthy of adoration, were simple bread and wine, after the invocation the bread becomes the body of Christ, and the wine the blood of Christ [Catechetical Lectures 19:7 (c. A.D. 350)].
Consider therefore the bread and the wine not as bare elements, for they are, according to the Lord’s declaration, the body and blood of Christ; for even though sense suggests this to you, let faith establish you. Judge not the matter from the taste, but from faith be fully assured without misgiving, that the body and blood of Christ have been vouchsafed to you. . . . Having learned these things, and been fully assured that the seeming bread is not bread, though sensible to taste, but the body of Christ; and that the seeming wine is not wine, though the taste will have it so, but the blood of Christ; and that of this David sung of old, saying, “And bread strengthens man’s heart, to make his face to shine with oil, strengthen your heart,” by partaking of it as spiritual, and “make the face of your soul to shine” [ibid., 22:6, 9].
St. Augustine of Hippo
I promised you, who have now been baptized, a sermon in which I would explain the sacrament of the Lord’s table. . . . The bread you see on the altar, having been sanctified by the word of God, is the body of Christ. The chalice, or rather, what is in the chalice, having been sanctified by the word of God, is the blood of Christ [Sermons 227 (c. A.D. 411)].
What you see is the bread and the chalice; that is what your own eyes report to you. But your faith obliges you to accept that the bread is the body of Christ and the chalice is the blood of Christ. This has been said very briefly, which may perhaps be sufficient for faith; yet faith does not desire instruction [ibid., 272].