The doctrine of the Real Presence of Christ in the Eucharist entails the idea that what is substantially there—the body and blood of Jesus—is not what our senses perceive, i.e., bread and wine. But isn’t that deception? Giving us a sacrament that deceives our senses doesn’t seem to fit the M.O. of an all-good God.
We can respond with St. Thomas Aquinas and say there is no deception. He gives two reasons why in his Summa Theologiae (III.75.5 ad 2).
First, the senses perceive what they are ordered to perceive—namely, the accidents of bread and wine (e.g., their color, size, shape, taste, smell, material quantity, etc.). The sensible qualities of bread and wine are what our senses are meant to capture. Our senses are not meant to capture the essence or substance of the thing. That’s the job of the intellect. So, our senses aren’t being deceived when they fail to capture the true essence of the consecrated bread and wine as Jesus’ real body and blood.
Now, someone might counter, “But doesn’t the intellect normally arrive at knowledge of a substance by way of its accidents? If so, then the intellect is deceived when told that what appears to be bread and wine is not.”
This leads us to the second reason why there is no deception: the intellect does in fact perceive the real substance of the Eucharist, but in a supernatural way—by faith. It’s true that the intellect naturally penetrates to the substance of a thing via its accidents. But the key is naturally.
The Eucharist is not natural; it’s supernatural. Thus, the intellect can’t penetrate to the substance of the Eucharist on its own. It needs some assistance to do its job. And that assistance comes through the gift of faith.
So, as Aquinas states, “[T]he intellect, who proper object is substance… is preserved by faith from deception.”
The mind’s judgment concerning the Eucharist is like its judgment that in Christ “the whole fulness of deity dwells” (Col. 2:9). According to what appears to our senses when looking at Christ, the mind would normally judge this man to be merely a man. But by the gift of faith, the intellect penetrates to the Word of God who is God (cf. John 1:1). There is no more deception in the Eucharist than there is in Jesus who is the Word of God made flesh.
Given the Incarnation, we can say that the Eucharist is the M.O. of an all-good God after all!