Imagine the following scenario: a small church, far more crowded than normal, perhaps because of some parish fundraiser or event that is to follow Mass that day. There are not enough consecrated hosts to go around, so Father is fracturing the hosts as he continues to distribute Holy Communion. In spite of his efforts, there are no more consecrated hosts left when you arrive before him. He looks at you with concern, an apology forming on his lips, and then you see the light bulb go off behind his eyes. He has an idea. He turns to the deacon who is holding the chalice and beckons him over. With visible relief, Father sees that the chalice is not empty. He offers it to you, saying, “The body of Christ.”
This is, admittedly, an unlikely situation, as priests tend to make an effort toward situational awareness! Perhaps the deacon was already returning the chalice to the altar for ablutions; there could be many variables here. I present it here as an extreme example, to help illustrate the point. Understanding how principles can be applied in extreme examples helps us to understand those principles better.
To bring us back down to earth, now let’s look at a likelier scenario: a parishioner who has a severe gluten allergy, which prevents him from being able to consume any sort of bread—or anything with all the physical attributes of bread, even if it is substantially Jesus Christ. Is such a person ineligible for receiving Holy Communion, since anything other than unleavened wheat bread would be invalid matter for the sacrament (this is why ministers can provide low-gluten hosts but not gluten-free ones), and thus not a validly confected Eucharist?
Thank God, no. Such an individual could still receive from the chalice. But, you might ask, doesn’t the chalice contain only Christ’s blood? After all, when the minister hands me the chalice, he says, “The blood of Christ,” just as the priest says, “The body of Christ” when he gives me the host. So if I receive only from the chalice, aren’t I missing out on something?
To answer this question, we will need to have a better understanding of just what the Church teaches about the real presence of Jesus Christ in the Eucharist.
The Church teaches that Jesus Christ is really, truly, and substantially present in the eucharistic species after the consecration—and that is Jesus in his entirety: body, blood, soul, and divinity. This is true of both species, even when only one is consumed. Of course, both the bread and wine will be present at every Mass, as these are the required matter for a valid Eucharist. But in many cases, only the priest will receive both the host and the contents of chalice, whereas the congregation receive only the host. In such a case, no one doubts whether he has received the Eucharist rather than some sort of incomplete portion.
The same is true for someone who only receives from the chalice:
The eucharistic presence of Christ begins at the moment of the consecration and endures as long as the eucharistic species subsist. Christ is present whole and entire in each of the species and whole and entire in each of their parts, in such a way that the breaking of the bread does not divide Christ (CCC 1377).
If we look carefully, we can see indications of this teaching in Scripture. For example, let’s take a look at St. Paul’s First Letter to the Corinthians, which is the only time outside the Gospels that we read an account of the Last Supper and the institution of the Eucharist. Paul provides some of the deepest theological reflections on the Eucharist that we have from the Church’s earliest days.
He writes, “Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For any one who eats and drinks without discerning the body eats and drinks judgment upon himself” (11:27-29).
There is one particular word I would like to draw attention to, packed with much more meaning than its two letters betoken: or. Paul says that if someone eats the bread or drinks the cup in an unworthy manner, he profanes the body and blood of the Lord. That little conjunction tells us a great deal about what Paul is describing: one need not partake of the bread in order to profane the body and blood. Even if one were to be in an unworthy state and drink only of the cup, he would profane the body and blood. This tells us that the body and blood are present in the contents of the cup.
We get a further elaboration of this point in the Catechism:
Since Christ is sacramentally present under each of the species, communion under the species of bread alone makes it possible to receive all the fruit of eucharistic grace. For pastoral reasons this manner of receiving communion has been legitimately established as the most common form in the Latin rite. But “the sign of communion is more complete when given under both kinds, since in that form the sign of the eucharistic meal appears more clearly.” This is the usual form of receiving communion in the Eastern rites (1390).
The Church has explained in the General Instruction of the Roman Missal,
Sacred pastors should take care to ensure that the faithful who participate in the rite or are present at it are as fully aware as possible of the Catholic teaching on the form of Holy Communion as set forth by the Ecumenical Council of Trent. Above all, they should instruct the Christian faithful that the Catholic faith teaches that Christ, whole and entire, and the true sacrament, is received even under only one species, and consequently that as far as the effects are concerned, those who receive under only one species are not deprived of any of the grace that is necessary for salvation (GIRM 282).
The point has been emphasized, as well, in response to questions regarding reception of Communion under one or the other species alone. Sometimes such concerns are due to pastoral reasons, or even medical reasons, such as alcoholism or alcohol intolerance, gluten intolerance, etc. The point emphasized here repeatedly, in all of these pastoral situations, is the fact that Christ is truly present in each species.
So what happens if you receive from just the chalice? Well, Deo gratias—you have still received Holy Communion. You have received Jesus Christ, body, blood, soul, and divinity.