The Second Vatican Council called the Eucharist the “source and summit of Christian life,” which was the theme of October’s Synod of Bishops devoted to the Eucharist. We claim the Eucharist to be the culmination of our relationship with God because it is the culmination of God’s relationship with us: the gift of his Son, Jesus Christ. In the Eucharist God is saving and sanctifying the world. One who desires a friendship with God will eventually come to hunger for Christ in the Eucharist.

Sadly, though, recent surveys suggest a weakening among Catholics of their belief in the Real Presence — the fact that at Mass bread and wine are transformed into the Body and Blood of Christ through what we call transubstantiation.

Our Lord’s choice of bread and wine as the “elements” of the Eucharist is filled with significance. To take what is ordinary and corruptible as the instrument for his enduring presence in the world reflects the very nature of the Incarnation. In Christ, the all-powerful God becomes weak and vulnerable, taking on a human nature, so that we weak and vulnerable humans can be one with him in his divinity. His sacred humanity draws us into communion with his divine nature, in the sacraments.

The mystery of Christ’s sacrificial death is at the heart of every Mass. For this reason it is called “the holy sacrifice of the Mass.” Going to Communion implies more than receiving Jesus Christ in his body and blood, soul and divinity, under the appearances of bread and wine. Our “Amen” signifies acceptance of the full meaning of the Eucharist, that only in his death and resurrection will we find the meaning and purpose of our own lives.

As “priestless Sundays” become more common, we risk losing the connection between the Eucharist and the Mass. Communion services can never offer the fullness of eucharistic activity. It is the sacrifice of Calvary, represented in an unbloody manner in the Mass, which is the source of the continuing presence of Christ in the Blessed Sacrament once the Mass is finished. Holy hours and exposition of the Blessed Sacrament must flow from this source and lead us back to this celebration.

Too often we think of the Mass as a means only to receive holy Communion or to “get” Jesus in the consecrated host. In fact, Jesus Christ receives us into communion with himself. He offers a share in his divine life and commissions us to take up the work of a disciple, to spread the Good News through a life of virtue and evangelization. There are consequences to holy Communion.

Receiving Christ requires proper preparation. The obvious obstacle is mortal sin. When one has not yet confessed a mortal sin, one must refrain from holy Communion. Mortal sin offends God and renders the sinner spiritually “dead” to grace. Proper preparation often entails the sacrament of reconciliation.

The one-hour eucharistic fast from solid food and liquids before Communion (with the exception of water and medicine) calls us to prepare interiorly for the Eucharist. Because we so quickly become mired in the affairs of the material world, this small discipline reminds us of our future in eternity, which is begun in the Eucharist.

Dominican Father Gabriel B. O’Donnell is director of the Order’s Catholic Information Service.