Today’s Catechism sections begin the topic of the Holy Eucharist. Supporting material comes from St. Irenaeus’ “Against Heresies”.

Article 3

THE SACRAMENT OF THE EUCHARIST

1322 The holy Eucharist completes Christian initiation. Those who have been raised to the dignity of the royal priesthood by Baptism and configured more deeply to Christ by Confirmation participate with the whole community in the Lord's own sacrifice by means of the Eucharist.

1323 "At the Last Supper, on the night he was betrayed, our Savior instituted the Eucharistic sacrifice of his Body and Blood. This he did in order to perpetuate the sacrifice of the cross throughout the ages until he should come again, and so to entrust to his beloved Spouse, the Church, a memorial of his death and resurrection: a sacrament of love, a sign of unity, a bond of charity, a Paschal banquet 'in which Christ is consumed, the mind is filled with grace, and a pledge of future glory is given to us.'"133

I. The Eucharist - Source and Summit of Ecclesial Life

1324 The Eucharist is "the source and summit of the Christian life."134 "The other sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward it. For in the blessed Eucharist is contained the whole spiritual good of the Church, namely Christ himself, our Pasch."135

1325 "The Eucharist is the efficacious sign and sublime cause of that communion in the divine life and that unity of the People of God by which the Church is kept in being. It is the culmination both of God's action sanctifying the world in Christ and of the worship men offer to Christ and through him to the Father in the Holy Spirit."136

1326 Finally, by the Eucharistic celebration we already unite ourselves with the heavenly liturgy and anticipate eternal life, when God will be all in all.137

1327 In brief, the Eucharist is the sum and summary of our faith: "Our way of thinking is attuned to the Eucharist, and the Eucharist in turn confirms our way of thinking."138

IN BRIEF

1406 Jesus said: "I am the living bread that came down from heaven; if any one eats of this bread, he will live for ever; . . . he who eats my flesh and drinks my blood has eternal life and . . . abides in me, and I in him" (⇒ Jn 6:51, ⇒ 54, ⇒ 56).

1407 The Eucharist is the heart and the summit of the Church's life, for in it Christ associates his Church and all her members with his sacrifice of praise and thanksgiving offered once for all on the cross to his Father; by this sacrifice he pours out the graces of salvation on his Body which is the Church.

St. Irenaeus discusses the Eucharist in “Against Heresies” (4, 18, 5).

5. Then, again, how can they say that the flesh, which is nourished with the body of the Lord and with His blood, goes to corruption, and does not partake of life? Let them, therefore, either alter their opinion, or cease from offering the things just mentioned. But our opinion is in accordance with the Eucharist, and the Eucharist in turn establishes our opinion. For we offer to Him His own, announcing consistently the fellowship and union of the flesh and Spirit. For as the bread, which is produced from the earth, when it receives the invocation of God, is no longer common bread, but the Eucharist, consisting of two realities, earthly and heavenly; so also our bodies, when they receive the Eucharist, are no longer corruptible, having the hope of the resurrection to eternity.

Footnotes

133 SC 47.
134 LG 11.
135 PO 5.
136 Congregation of Rites, instruction, Eucharisticum mysterium, 6.
137 Cf. ⇒ 1 Cor 15:28.
138 St. Irenaeus, Adv. haeres. 4, 18, 5: PG 7/l, 1028.