The biblical foundation for Holy Communion is what Christ Himself did at the Last Supper. As narrated by St. Matthew, Jesus first offered the apostles what He was about to change, then changed the bread and wine, and then gave them Communion.
And while they were at supper, Jesus took bread and blessed and broke and gave it to His disciples and said, “Take you and eat, this is my Body.” And taking the chalice He gave thanks and gave it to them saying, “Drink you all of this. For this is my Blood of the New Testament which shall be shed for many unto remission of sins.” (Matthew 26:26-28)
St. John, who does not give us the narrative of the institution of the Eucharist, devotes a whole chapter to Christ’s promise of giving His followers His own flesh to eat and His own blood to drink. What Christ emphasizes is the absolute necessity of being nourished by His Body and Blood if the supernatural life received at Baptism is to be sustained.
I tell you most solemnly, if you do not eat the flesh of the Son of Man and drink His blood, you will not have life in you. Anyone who does eat my flesh and drink my blood has eternal life and I shall raise him up on the last day. For my flesh is real food and my blood is real drink. He who eats my flesh and drinks my blood lives in me and I live in Him. As I, who am sent by the living Father, myself draw life from the Father, so whoever eats me will draw life from me. This is the bread come down from heaven; not like the bread our ancestors ate. They are dead, but anyone who eats this bread will live forever. (John 6: 53-58)
Throughout the gospels and St. Paul, Christ uses words like “take,” “eat,” “drink,” always clearly indicating that the Eucharist is to be taken into the mouth and consumed. No less, and far more, than material food and drink are necessary to sustain the natural life of the body, so Holy Communion must be received to support and nourish the supernatural life of the soul.
Effects of Holy Communion
Since the earliest times, the benefits of receiving the Body and Blood of Christ were spelled out to encourage frequent, even daily, Holy Communion.
Thus, St. Cyril of Jerusalem (died 387) said that reception of the Eucharist makes the Christian a “Christbearer” and “one body and one blood with Him” (Catecheses, 4,3). St. John Chrysostom (died 407) speaks of a mixing of the Body of Christ with our body, “…in order to show the great love that He has for us. He mixed Himself with us, and joined His Body with us, so that we might become one like a bread connected with the body” (Homily 46,3). These and other comparisons of how Communion unites the recipient with Christ are based on Christ’s own teaching, and St. Paul’s statement that, “the bread which we break, is it not the partaking of the Body of the Lord? For we, being many, are one bread, all that partake of this bread.” (I Corinthians 10:16-17).
So, too, the church officially teaches that “Every effect which bodily food and bodily drink produce in our corporeal life, by preserving this life, increasing this life, healing this life, and satisfying this life – is also produced by this Sacrament in the spiritual life” (Council of Florence, November 22, 1439). Thus:
Holy Communion preserves the supernatural life of the soul by giving the communicant supernatural strength to resist temptation, and by weakening the power of concupiscence. It reinforces the ability of our free will to withstand the assaults of the devil. In a formal definition, the Church calls Holy Communion “an antidote by which we are preserved from grievous sins” (Council of Trent, October 11, 1551).
Holy Communion increases the life of grace already present by vitalizing our supernatural life and strengthening the virtues and gifts of the Holy Spirit we possess. To be emphasized, however, is that the main effect of Communion is not to remit sin. In fact, a person in conscious mortal sin commits a sacrilege by going to Communion.
Holy Communion cures the spiritual diseases of the soul by cleansing it of venial sins and the temporal punishment due to sin. No less than serving as an antidote to protect the soul from mortal sins, Communion is “an antidote by which we are freed from our daily venial sins” (Council of Trent, October 11, 1551). The remission of venial sins and of the temporal sufferings due to sin takes place immediately by reason of the acts of perfect love of God, which are awakened by the reception of the Eucharist. The extent of this remission depends on the intensity of our charity when receiving Communion.
Holy Communion gives us a spiritual joy in the service of Christ, in defending His cause, in performing the duties of our state of life, and in making the sacrifices required of us in imitating the life of our Savior.
On Christ’s own promise, Holy Communion is a pledge of heavenly glory and of our bodily resurrection from the dead (John 6:55). St. Irenaeus (died 202) simply declared that, “when our bodies partake of the Eucharist, they are no longer corruptible as they have the hope of eternal resurrection” (Against the Heresies, IV, 18,5).