Some Jews, seeing and hearing of the great miracles performed by the Lord Jesus Christ, expressed the desire that the Lord would work a sign before them similar to what Moses showed the Jewish people when he gave them manna from Heaven.
In response, the Lord told them that this manna was given them not by Moses, but the Heavenly Father; that manna didn’t make those who partook of it immortal, for all those who ate of it died. And now the Heavenly Father gives them another bread, which comes down from Heaven and gives life to the world. Those who partake of this bread won’t die as did those who ate the manna. To this, the Jews said: Lord, evermore give us this bread (Jn. 6:34). The Lord told them: I am the living bread which came down from Heaven: if any man eat of this bread, he shall live for ever: and the bread that I will give is My flesh (Jn. 6:51). Then the Jews said: How can this man give us His flesh to eat? (Jn. 6:52). The Lord didn’t explain this to them—for the time for it hadn’t yet come and they weren’t able to receive His words—but only further confirmed His words about the need for all to taste of this Bread of Life: Except ye eat the flesh of the Son of Man, and drink His blood, He said, ye have no life in you (Jn. 6:53).
Every Christian must remember these words of the Lord about His Most Pure Body and Blood, and they are especially useful for the people of our times. For there are among us Christians who, like the Jews, are ready to ask: “How can Christ give us His Flesh? He’s in Heaven, and we don’t see that He Himself gives us His Body and Blood from Heaven to partake of. When He was with the Apostles, He Himself gave them Holy Communion under the form of bread and wine, which He was able to transform into His Body and Blood—and now He’s not here, and the Sacrament is celebrated by people who are, perhaps, unworthy. How can we be sure that the Body of Christ is really being given under the appearance of bread, and His true Blood under the appearance of wine?”
Let’s try to clarify this as much as possible. The Communion of the Body and Blood of Christ is a Sacrament [Mystery]. It’s so called because it’s a mystery, incomprehensible to the human mind, but perceived by faith. The Sacrament of Communion is one of the seven Sacraments through which the faithful are given grace. It’s impossible to comprehend how the Sacrament of the Body and Blood of Christ is celebrated—that is, how bread is transformed into the Body and wine into the Blood of Christ. But it’s impossible for anyone who believes in Christ and believes His words to doubt that this is truly the case.
All the Sacraments in the Church are established by the Lord Himself. The authority to celebrate the Sacraments and give saving grace was first received by the Holy Apostles from the Lord Himself, Who sent them the Holy Spirit to this end (Jn. 20:22). The Apostles transferred this authority and grace of the Holy Spirit to their successors. From the Apostles, such grace of the priesthood passes successively to all validly appointed bishops and priests. This unbroken chain of the priesthood has successively come down to our time. And in our time, salvific grace is given through the Sacraments celebrated by validly established bishops and priests. Every priest who is validly appointed by a bishop is ordained a priest by God Himself.
How we do know that God ordains priests through bishops? St. John Chrysostom answers as follows:
If you’re not convinced of this, that a priest receives the grace of the priesthood from God, then your hope is in vain, because if God doesn’t do anything through a priest, then you don’t have Baptism, you don’t commune of the Holy Mysteries, you don’t receive a blessing—therefore, you’re not a Christian.
Therefore, that which you, Christian, commune of from the hand of the priest under the appearance of bread and wine is that very Body that the Lord gave to the Apostles under the appearance of bread, that very Blood that He gave them under the appearance of wine. But you may ask: “How can bread change its property and become Body, and wine—Blood?” We will respond: Just as the five loaves with which the Lord fed the five thousand (Mt. 14:17-20) changed their property, and as the water turned into wine at the wedding in Cana of Galilee (Jn. 2:3-11).
It's not only non-believers or people who have fallen away from faith who can have doubtful thoughts about Holy Communion, but they can also sometimes confound even the pious, through the enemy’s delusions.
The Lord sometimes admonished and admonishes such people with special revelations for their benefit and for that of others who are confounded by similar thoughts.
In The Prologue, there is the following story about a monk who, under devilish delusion, was disturbed by doubts about Communion:
It was told about a certain brother that when there was a Church gathering on Sunday, he would get up and go to church according to custom, but the devil mocked him, putting this thought into him: “You’re going to church to receive bread and wine as the Body and Blood of Christ? Don’t disgrace yourself; don’t go!” The brother listened to this conjecture and didn’t go to church.
Meanwhile, the brethren were waiting for him, for this hermitage had the custom of not starting the services until all the brethren had gathered. When after a long wait the brother still hadn’t come, several of them got up and went to his cell, saying: “You haven’t gotten sick or died, have you, brother?” When they got to his cell, they asked him: “Brother, why haven’t you come to church?” He was ashamed to tell them the truth.
Then they realized that the devil had inspired him with some insidious advice, and prostrating at his feet, they begged him to tell them this diabolical though. Then he told them: “Forgive me, brothers! When I got up to go to church as usual, a thought said to me: ‘There is no Body and Blood of Christ—why are you going to receive simple bread and wine?’ Thus, if you want me to go with you, free my thought from doubt about Holy Communion.”
They told him: “Get up, come with us, pray to God, and He will help you and reveal His mystical power, and will make the invisible visible.”
He got up and went with them. They prayed for the brother, that God might reveal the power of the Divine Mysteries to him. Then, when the time came for Church prayer, they put the brother in the middle of the church. He wept incessantly throughout the entire service. After the dismissal, the fathers and brothers called him and asked: “Tell us what God revealed to you, so we might also benefit.”
Then he began to tearfully tell them the following: “When you were doing the usual singing, the Apostolic teaching was read, and the deacon began to read the Gospel, then I saw how the top of the church opened up and I could see Heaven; every Gospel word descended like fire from Heaven. When the Gospel had been read and the deacons were carrying the Communion of the Divine Mysteries, I also saw the heavens open and fire descending from there with many holy angels; above them I saw two Faces, so beautiful that it’s impossible to describe how beautiful they were: They shone like lightning. In the midst of these two Faces was a Boy; the angels were standing near the Holy Table, and these two Faces over the Holy Table, and amidst Them a Child.
After the Divine Mysteries were celebrated, the deacons went from the kliros to distribute the Bread of the Offering, and I saw two Faces, fanning over the Holy Table. They bound the hands and feet of the Child, sacrificed Him with a knife that They had, and His Blood poured into the chalice on the Holy Table. His Body was crushed and placed on top the bread, and the bread became His Body. Then I recalled the Apostle’s words: Christ our Pascha [Passover] is sacrificed for us (1 Cor. 5:7). When the brethren approached to receive the Holy Gifts, they were given the Body, and when they said: “Amen,” then it turned out to be Bread in their hands.
When I approached and the Body was handed to me, I couldn’t accept it, and I heard a voice in my ears, saying: “Man! Why don’t you receive it? Is it really not what you were looking for?” I said: “God, be merciful to me. I can’t receive Thy Body,” and again it was said to me: “If man could receive My Body, then My Body would be found as you found it; but no one can eat Body, therefore God has commanded that Bread be offered. If you believe, receive what you hold in your hands.” I said: “I believe, O Lord!” and when I said: “Amen,” the Body in my hands became Bread. I praised God and received the Holy Gifts.
When the service ended and all the clergy came out, I again saw the Child amidst two Faces, and the clerics were consuming the Gifts at this time. After that, the church roof again opened up and I saw the Divine Powers ascending to Heaven, and the Child among them.”
Having heard this, the brethren were greatly comforted and returned to their cells, glorifying God the Father.
Let us conclude our conversation about Holy Communion with the testimony of the holy Apostle Paul, who received the teaching about this most holy Sacrament by revelation from the Lord Himself. The cup of blessing which we bless, he says, is it not the Communion of the Blood of Christ? The bread which we break, is it not the Communion of the Body of Christ? (1 Cor. 10:16). But let a man examine himself, and so let him eat of that Bread, and drink of that Cup. For he that eateth and drinketh unworthily, that is, without faith, without purification of conscience, without reverence, eateth and drinketh damnation to himself, not discerning the Lord’s Body (1 Cor. 11:28-29).