The invitation to Communion appeals to the notion of oblation or of the “lamb” being the sacrament of Jesus Christ. After a genuflection, the priest holds the sacred host slightly above the paten or chalice while facing the people and says: “Behold the Lamb of God, behold him who takes away the sins of the world. Blessed are those who are called to the supper of the Lamb.” Along with the people, he adds: “Lord, I am not worthy that you should enter under my roof, but only say the word and my soul shall be healed.”
John the Baptizer at the Jordon points Jesus out to his followers: “Behold, the Lamb of God, who takes away the sin of the world” (John 1:29) and “Behold, the Lamb of God!” (John 1:37). He urges the apostle John and Andrew (brother of Peter) to go to Jesus.
The words, “Lord, I am not worthy” express the existential state of all creation as dependent and unworthy of the gifts and divine mercy shown us. God loves us and saves us, not because we are good but because we are bad and he desires to make us good. At every Mass, we acknowledge that the Jewish Messiah is the Savior for all the world. We all play the part of the great believing Gentile, the Roman Centurion (Matthew 8:5-11).
When Jesus entered Capernaum, a centurion approached him and appealed to him, saying, “Lord, my servant is lying at home paralyzed, suffering dreadfully.” He said to him, “I will come and cure him.” The centurion said in reply, “Lord, I am not worthy to have you enter under my roof; only say the word and my servant will be healed. For I too am a man subject to authority, with soldiers subject to me. And I say to one, ‘Go,’ and he goes; and to another, ‘Come here,’ and he comes; and to my slave, ‘Do this,’ and he does it.” When Jesus heard this, he was amazed and said to those following him, “Amen, I say to you, in no one in Israel have I found such faith. I say to you, many will come from the east and the west, and will recline with Abraham, Isaac, and Jacob at the banquet in the Kingdom of heaven.”
The formula in use here may have evolved from the practice of taking Holy Communion to the sick in their homes. Associated with the Eucharist it would readily find inclusion in the Mass. The centurion does not need to see so as to believe. The word of Christ is enough. Approaching Communion we believe two things: (1) we are encountering the risen Christ present in the Eucharist and (2) we are availing ourselves of his mercy and his miraculous healing power.