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.
“At the Last Supper, on the night he was betrayed, our Saviour 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.'”
The Eucharist is “the source and summit of the Christian life.” “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.”
“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.”
Finally, by the Eucharistic celebration we already unite ourselves with the heavenly liturgy and anticipate eternal life, when God will be all in all.
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.” (Catechism of the Catholic Church, paragraphs 1322-1327)
Rogier Van Der Weyden, The Seven Sacraments (detail)