Today the Church celebrates the doctrine that, perhaps more than any other, defines us as Catholics within the Christian community. It is the faith of the Church that in the Mass, at the Consecration, there is a real and substantial change in the bread and wine in which they become really and truly the Body and the Blood of Christ.
The traditional theological term (from Saint Thomas Aquinas, using the philosophical language of Aristotle, for this change is Transubstantiation. The Latin word “trans” means to cross over, to go beyond. There is a real crossing over from the substance of bread and wine to something different—the substance of the Body and Blood of Christ. This is not just a symbolic change but a real change.
When we receive Communion, it is Jesus Christ himself that we receive. We are not receiving a piece of Jesus, but the whole and entire Jesus Christ himself. This is true if we receive a tiny piece of the host or a tiny sip from the cup. We do not receive more Jesus if we receive from both the cup and the host. Each is the fullness of Jesus—Body, Blood, Soul and Divinity.
— Fr. Michael Comer