The bread and the wine of the Eucharist before the holy invocation of the adorable Trinity were simple bread and wine, but the invocation having been made, the bread becomes the body of Christ and the wine the blood of Christ.
Do not, therefore, regard the bread and wine as simply that; for they are, according to the Master’s declaration, the body and blood of Christ. Even though the senses suggest to you the other, let faith make you firm. Do not judge in this matter by taste, but be fully assured by the faith.
As for why is a Catholic not allowed to receive communion in any other denomination, the answers are several.
- because we know that, as they too profess but for other reasons, that bread and wine is not the true body and blood of Christ, but a symbolic offering, yet “our own eyes have seen the salvation which He has prepared in the sight of every people, a light to reveal Him to the nations, and the glory of His people”. By not partaking in any Communion but the Bread of Life and the Chalice of Salvation, we lead people towards Christ. This is done with great love and humbleness.
- because such was the instruction we received from the apostolic tradition, when already we had separated communities. For instance, the same Ignatius of Antioch exhorts us not to follow a maker of schism or walk in a strange doctrine, and clarifies:
Take care, then, to use one Eucharist, so that whatever you do, you do according to God: For there is one flesh of our Lord Jesus Christ, and one cup in the union of his blood; one altar, as there is one bishop, with the presbytery and my fellow servants, the deacons.
Another Church Father, Jerome, translated to Latin the first and greatest Bible, the Biblia Sacra Vulgata, which for a thousand years was the definite edition, and even after protestantism developed it was regarded as the standard scholarly Bible. Well, this is what he wrote to the bishop of Rome:
the assaults that I suffer in the desert are severer than ever …] The church is rent into three factions, and each of these is eager to seize me …] I meantime keep crying: “He who clings to the chair of Peter is accepted by me.” …] I follow no leader but Christ and join in communion with none but Your Blessedness, that is, with the chair of Peter. I know that this is the rock on which the Church has been built.
A good reading for her could be “
History of the Catholic Church from the Apostolic Age to the Third Millennium” by Dr. James Hitchcock.
Finally, from Catholic to Catholic, it is forbidden for us by Canon Law to receive Communion in any place other than the Catholic Church: “
Catholic members of Christ’s faithful … may lawfully receive them [the Sacraments] only from Catholic ministers” (# 844.1). However, only a Catholic readily realizes that this is not why we don’t receive communion in other denominations, but simply the codification of the rule, where the reasons are to be found in the deposit of faith, and these are what lead someone to understanding and fulfilling the law.
