(b) Communication is public, when the rites performed are the official services of the Catholic Church or of some non-Catholic sect (e.g., the Mass, the Lord’s Supper of the Lutherans, the Evensong of the Anglicans, the prayer-meeting of other sects). Thus, public communication takes place either when non-Catholics take part in Catholic worship, or Catholics take part in non-Catholic worship.
957. Participation of non-Catholics in Catholic services is either by mere presence, or by reception or performance of Catholic rites.
(a) Mere presence consists in a purely material attendance at a service, as when non-Catholics assist at Mass and sit, rise and kneel with the congregation or remain seated throughout. There is no objection whatever to this kind of participation; on the contrary, non-Catholics should be invited to Catholic sermons and services, and made to feel welcome, for in what better way can the divine command of working for their conversion be complied with? Only excommunicated persons are excluded from the offices of the Church (Canon 2269, Sec.1). It is also allowed that Catholic bishops and clergy accompany a non-Catholic ruler to the church, and assign him and his escort an honorable place therein.
(b) Reception of Catholic rites is had when non-Catholics, without performing any liturgical function, receive some spiritual favor through the rites of the Church, as when a non-Catholic receives a priest’s blessing.
(c) Performance of Catholic rites exists when a non-Catholic exercises some office in a liturgical function of the Catholic Church, as when a Protestant acts as sponsor at a Catholic Baptism.
958. Cases of reception of Catholic rites by non-Catholics permitted by law are the following:
(a) Reception of Sacramentals.—Since the purpose of these rites and objects is to implore graces and temporal favors with a view to the illumination and salvation of the recipient, and since our Lord Himself blessed and cured even the pagans, the Church permits blessings and exorcisms to be conferred on non-Catholics (Canons 1149, 1152). Similarly, blessed candles, palms, ashes and other real sacramentals may be given to them. Examples: The Church has permitted priests to visit the homes of Mohammedans to bless and pray over the sick, and also to bless the houses of schismatics, provided they were summoned and avoided all communication in prayer.
(b) Reception of Sacraments.-Since it is possible that the salvation of a dying person may depend on absolution, good moralists, relying on decisions of Roman Congregations, hold that conditional absolution may be given to a heretic or schismatic who is dying and unconscious, or even to one such who is dying and conscious, provided he is in good faith and contrite, and danger of scandal has been removed.
(c) Reception of Fruits of the Mass.—Since Christ died for all, there is nothing in the nature of things to prevent the application of Mass to any persons who are living or in Purgatory; and from Canon 809 it appears that Mass may be offered for any living person, and also for any deceased person about whose salvation we may entertain hope. Hence, neither the divine nor the ecclesiastical law forbids the application of Mass for heretics, schismatics, or infidels. The Church also permits Mass to be said privately, all scandal removed, for excommunicated persons. Under these same conditions, then, Mass may be said for non-Catholics, both living and dead (Canon 2262, Sec.2, n. 2).
(d) Reception of the Suffrages of the Church.—Since God wishes all to be saved and public peace to be maintained (I Tim., ii), and since the Church desires that Ordinaries and pastors should have at heart the conversion of non-Catholics (Canon 1350), public prayers for the prosperity of non-Catholic rulers and officials—likewise sermons, missions and other works for the conversion of unbelievers—are not only allowed, but recommended and required.