As Catholics, we believe that the celebration of the Eucharist is a sign of our oneness in faith, life and worship. Members of churches with whom we are not yet fully united are therefore not ordinarily invited to participate in Holy Communion. The Catechism of the Catholic Church reflects on this teaching.
Ecclesial communities derived from the Reformation and separated from the Catholic Church, "have not preserved the proper reality of the Eucharistic mystery in its fullness, especially because of the absence of the sacrament of Holy Orders." It is for this reason that Eucharistic intercommunion with these communities is not possible for the Catholic Church. However these ecclesial communities, "when they commemorate the Lord's death and resurrection in the Holy Supper ... profess that it signifies life in communion with Christ and await his coming in glory." (Catechism of the Catholic Church, number 1400)
Members of the Orthodox churches and the Polish National Catholic Churches share a more intimate bond with us, however. They may receive the Eucharist when they ask for it and they are properly disposed (cf. Canon 844). Again, we refer to the Catechism of the Catholic Church:
The Eastern churches that are not in full communion with the Catholic Church celebrate the Eucharist with great love. "These Churches, although separated from us, yet possess true sacraments, above all - by apostolic succession - the priesthood and the Eucharist, whereby they are still joined to us in closest intimacy." A certain communion in sacris...is not merely possible but is encouraged." (Catechism of the Catholic Church, number 1399)
When other Christians who believe what the Catholic church teaches concerning the Holy Eucharist are deprived of access to a church of their own denomination for a significant period of time, they too may be admitted to Communion in the Catholic Church in exceptional circumstances (cf. Canon 844 §4). These exceptional circumstances are also described by the Catechism of the Catholic Church:
When, in the Ordinary's judgment, a grave necessity arises, Catholic ministers may give the sacraments of Eucharist, Penance, and Anointing of the Sick to other Christians not in full communion with the Catholic Church, who ask for them of their own will, provided they give evidence of holding the Catholic faith regarding these sacraments and possess the required dispositions. (Catechism of the Catholic Church, number 1401)
On November 14, 1996, the National Conference of Catholic Bishops approved the following guidelines on the reception of communion. These guidelines replace the guidelines approved by the Administrative Committee of the NCCB in November 1986. The guidelines, which are to be included in missalettes and other participation aids published in the United States, seek to remind all those who may attend Catholic liturgies of the present discipline of the Church with regard to the sharing of eucharistic communion.
As Catholics, we fully participate in the celebration of the Eucharist when we receive Holy Communion. We are encouraged to receive Communion devoutly and frequently. In order to be properly disposed to receive Communion, participants should not be conscious of grave sin and normally should have fasted for one hour. A person who is conscious of grave sin is not to receive the Body and Blood of the Lord without prior sacramental confession except for a grave reason where there is no opportunity for confession. In this case, the person is to be mindful of the obligation to make an act of perfect contrition, including the intention of confessing as soon as possible (canon 916). A frequent reception of the Sacrament of Penance is encouraged for all.
For our fellow Christians
We welcome our fellow Christians to this celebration of the Eucharist as our brothers and sisters. We pray that our common baptism and the action of the Holy Spirit in this Eucharist will draw us closer to one another and begin to dispel the sad divisions which separate us. We pray that these will lessen and finally disappear, in keeping with Christ's prayer for us "that they may all be one" (Jn 17:21).
Because Catholics believe that the celebration of the Eucharist is a sign of the reality of the oneness of faith, life, and worship, members of those churches with whom we are not yet fully united are ordinarily not admitted to Holy Communion. Eucharistic sharing in exceptional circumstances by other Christians requires permission according to the directives of the diocesan bishop and the provisions of canon law (canon 844 § 4). Members of the Orthodox Churches, the Assyrian Church of the East, and the Polish National Catholic Church are urged to respect the discipline of their own Churches. According to Roman Catholic discipline, the Code of Canon Law does not object to the reception of communion by Christians of these Churches (canon 844 § 3).
For those not receiving Holy Communion
All who are not receiving Holy Communion are encouraged to express in their hearts a prayerful desire for unity with the Lord Jesus and with one another.
We also welcome to this celebration those who do not share our faith in Jesus Christ. While we cannot admit them to Holy Communion, we ask them to offer their prayers for the peace and the unity of the human family.