Last Sunday we celebrated the Holy Trinity, the doctrine that identifies us as Christian. This Sunday we celebrate the Feast of the Body and Blood of Christ (Corpus Christi), the doctrine which most identifies us as Catholic.
In the Mass, bread and wine are brought forward and are offered by the priest. At that time, the bread and the wine represent us—our lives, our family life, our work, our joys, our struggles and pain, etc. So, what we do is offer our lives to God, imperfect as they are. God then sends His Holy Spirit upon the bread and wine to sanctify them. He then changes them so that they become the Body and Blood of Jesus Christ.
Jesus spoke clearly on what happens in these moments. In the Bread of Life Discourse, in the sixth chapter of the Gospel of John, Jesus identifies Himself as the Bread from Heaven, and that we must eat His Body and drink His Blood, or we will not have life within us. He tells us that His Flesh is real food and His Blood is real Drink. In all three of the Institution Accounts, He takes the bread, and says, “This is my Body.” And He takes the cup and says, “This is the cup of my Blood.” And finally, St. Paul tells the Corinthians that those who eat and drink the Eucharist unworthily eat and drink condemnation on themselves, and that is why some are getting sick, and even dying.