Since the doctrine of the Real Presence (that Jesus is literally and wholly present--body and blood, soul and divinity--under the appearances of bread and wine) is frequently attacked by Evangelicals and Fundamentalists as "unbiblical," it's crucial that we examine the writings of the Church Fathers to discover what the earliest Christians, the people to and about whom the New Testament was written, believed about it.
But first let's look briefly at the scriptural basis for the doctrine of the Eucharist.
The Bible teaches that Jesus is really, not just symbolically, present in the Eucharist (Matt. 26:26-28; Mark 14:22-24; Luke 22:19-20; 1 Cor. 10:16-17; 1 Cor. 11:23-29; and, most forcefully, John 6:32-71).
Evangelicals and Fundamentalists don't view these verses as proof that the Eucharist is a biblical doctrine and argue against it by quoting Jesus' words in John 6:63: "It is the spirit that gives life, while the flesh is of no avail. The words I have spoken to you are spirit and life." They seize on the word "spirit" and interpret it as "symbolic," arguing that Jesus' use of "spirit" meant he was speaking symbolically, not literally.
Several questions should be asked at this point: (1) Where else in the Bible is "spirit" ever interpreted as "symbolic"? (The answer: Nowhere.) (2) Since there's no other instance of "spirit" meaning "symbolic," by what criteria do Protestants insist on applying that meaning in John 6:63? (3) Since God, human souls, angels, and Satan are spirits, does that mean they too are merely symbolic--and if not, why interpret "spirit" in John 6:63 as meaning "symbolic"?
Let's look at some examples of what the Fathers of the Church taught regarding the Eucharist.
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" (Epistle to the Romans 7:3 [A.D. 110]).
Ignatius of Antioch
"Take note of those who hold heterodox opinions on the grace of Jesus Christ which has 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 which suffered for our sins and which that Father, in his goodness, raised up again. They who deny the gift of God are perishing in their disputes" (Epistle to the Smyrnaeans 6:2; 7:1 [A.D. 110]).
"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 which is for the remission of sins and for regeneration [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 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 nurtured, is both the flesh and the blood of that incarnated Jesus" (First Apology 66:1-20 [A.D. 148]).
"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 4:33-32 [A.D. 148]).
"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 unto our bodies.
"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 eternal life--flesh which is nourished by the body and blood of the Lord, and is in fact a member of him?" (Against Heresies 5:2 [A.D. 148]).
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" (Paidagogos 1:6;43;3 [A.D. 202]).
Cyril of Jerusalem
"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" (Catechetical Discourses, Mystagogic 1, 19:7 [A.D. 350]).
Cyril of Jerusalem
"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 you firm.
"Do not judge in this matter by taste, but be fully assured by the faith, not doubting that you have been deemed worthy of the body and blood of Christ...[Since you are] fully convinced that the apparent bread is not bread, even though it is sensible to the taste, but the body of Christ, and that the apparent wine is not wine, even though the taste would have it so,...partake of that bread as something spiritual, and put a cheerful face on your soul" (Catechetical Discourses; Mystagogic 4, 22:9 [A.D. 350]).
Theodore of Mopsuestia
"When [Christ] gave the bread he did not say, 'This is the symbol of my body,' but, 'This is my body.' In the same way, when he gave the cup of his blood he did not say, '‘This is the symbol of my blood,' but, 'This is my blood'; for he wanted us to look upon the [Eucharistic elements] after their reception of grace and the coming of the Holy Spirit not according to their nature, but receive them as they are, the body and blood of our Lord. We ought...not regard [the elements] merely as bread and cup, but as the body and blood of the Lord, into which they were transformed by the descent of the Holy Spirit" (Catechetical Homilies 5:1 [A.D. 428]).
Jesus explained the Eucharist best: "My flesh is true food, and my blood is true drink. Whoever eats my flesh and drinks my blood remains in me and I in him" (John 6:55) .