The final sacrament of initiation is the Most Holy Eucharist where Christ is wholly present—Body, Blood, Soul, and Divinity— under the appearances of bread and wine. The Catechism of the Catholic Church notes,
“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” (1322).
This is the only repeatable Sacrament of Initiation. Therefore, each time we receive the Eucharist, our initiation into the Paschal Mystery of Christ is completed and hopefully deepened. In the celebration of the Eucharistic liturgy, we “unite ourselves to the heavenly liturgy and anticipate eternal life” (CCC 1326). Lumen gentium, the Dogmatic Constitution on the Church from Vatican II, teaches that the Eucharist is the “source and summit” of our faith (no. 11). This means that the other sacraments, and indeed all actions of the Church, flow from the Eucharist and all the actions of the Church are directed toward the Eucharist as the summit. As the Eucharist is our manna in the desert of this life, it sustains us on our journey toward our heavenly home. A sacrifice of thanksgiving to the Father (CCC 1360), the sacrifice of Christ on the cross and the Eucharist are one and the same (1367). Christ is present in the Eucharist from the moment of consecration and endures as long as the species of bread and wine subsist. He is wholly present in both species and in each of their parts: breaking the host does not divide Him (CCC 1377).
The Holy Eucharist is also a Sacrament of Healing. When worthily receiving the Eucharist, we are united to Christ. The Eucharist cleanses us from past sins and preserves from future sins in order to fully unite us to Jesus (CCC 1393).
Who can receive? In the Latin Church, Catholics who have reached the age of reason (usually 7) and who are not conscious of any mortal sins (CCC 1417). Sacramental confession of mortal sins is required prior to reception (CCC 1457). We are required to receive at least once per year during the Easter season and as often as daily.
Form, Matter, and Minister
Form: “This is my Body, which will be given up for you. … This is the chalice of my Blood, the Blood of the new and eternal covenant, which will be poured out for you and for many, for the forgiveness of sins. (CCC 1417; 1 Corinthians 11:24-25)
Matter: wheat bread (made of only wheat flour and water); unadulterated grape wine (can be red or white)
Minister: a validly ordained priest (or bishop) who, while saying the form, has the intent of confecting the Eucharist