The following are some thoughts I wrote to my Evangelical teammates here in Taiwan, in order to prepare them for the Easter Vigil and why non-Catholics cannot receive the Eucharist in Mass. I think they put the Sacraments in the proper context of the grand Sacrament of Salvation, the Church.
The Church is what Christ uses to reach the world today just as Christ was what God used to reach the world “back then.” As His Body, the Church is modeled on our Lord. Since Christ was not merely a spiritual or emotional entity, neither is His Church. Our Lord was a man of flesh and blood, and his grace was communicated precisely through those "mundane" materials. Being formally unified with the Church is as "mundane" and "material" a requirement as touching Jesus' body was to fully encounter Him back in the day. This is the basis for the sacraments themselves: they are the material channels God has given the Church so He can convey His grace into Christians, so that we, in turn, can convey His grace into the world. The sacraments are the “hem” of Christ’s garment, from which His power flows. In the Incarnation, and today in the Church’s sacraments, the materiality is not pitted against the spirituality, nor is formality pitted against faith. The Eucharist is the fullness of Christ's offer to mankind today. Receiving this gift entails mankind be as fully – officially and spiritually – united to His Body as possible. Agreeing to be formally united to the Catholic Church means you agree with its view of the Eucharist and desire to be just as formally and fully united with Christ himself in that gift. The reverse is true as well: desiring to receive Christ in Body, Blood, Soul and Divinity means signing on formally to the Catholic Church (or the Orthodox Churches).
Thus shall my “report” on the Sacraments end. I admit I feel kind of silly “explaining” the Sacraments. They are mysteries. They are existential realities which invite us to encounter God, not to examine them self-referentially. The Sacraments are the grips of God’s grace as we totter or tumble (or dive!) over a sea of sin. And as little as I would “explain” the how and the what of a man’s saving grasp on me as I nearly plummeted off a cliff, so little inclined am I to “understand” the Mysteries as I encounter God in them. Come, let us be on our way!