Today our Roman Catholic Church celebrates what is the “source, summit and font” of our Faith: that we believe in the act of Consecration, that the validly-ordained priest or bishop makes the mere bread and wine become the Body, Blood, Soul and Divinity of Jesus Christ at the Mass. That in the words of Consecration, the Real Presence of Christ comes into being.
This separates us from other Christian denominational churches that only believe in the Eucharist as a symbol of Christ—they do not believe in the Real Presence. This is why they have no issue with accepting those who do not share a faith belief into the reception of “communion”. Roman Catholics, on the other hand, reserve the reception of Holy Communion to those who share in the belief that the bread and wine become the Body, Blood, Soul and Divinity; it is not an attitude of “we are better than others” but that we so truly believe in the Real Presence of Christ that we hold the Eucharistic meal sacred, that we hold it in such high regard, that we honor it with due respect. If one does not hold the Eucharistic meal to be the Real Presence, the Body, Blood, Soul and Divinity of Christ, then why would one want to receive it?
I once heard a Rabbi speak to the issue of respecting other faith beliefs—as well as our own faith beliefs— while we are visiting in another house of worship, the goal should not be to adapt their beliefs out of kindness or to feel comfortable while in an unfamiliar house of worship or ritual, but rather to hold firm to what we belief and honor our own teachings while at the same time respecting the teachings of the house of worship in which we are a welcomed visitor. Just a new perspective on an age-old concern