A priest, who knowingly and willingly chooses to attempt to exercise priestly ministry outside of the communion of the Church and, thereby, assists and encourages others in breaking communion with the Church, clearly **also commits the ecclesiastical crime of schism. **--------------------
**Those who commit the ecclesiastical crime of schism incur automatically the penalty of excommunication **(cf. can. 1364, §1; and 1314). The excommunicated person is forbidden “to have any ministerial participation in celebrating the Sacrifice of the Eucharist or any other ceremonies of worship whatsoever” (can. 1331, §1, 1º); “to celebrate the sacraments or sacramentals, and to receive the sacraments” (can. 1331, §1, 2º); and “to exercise any ecclesiastical offices, ministries or functions whatsoever or to place acts of governance” (can. 1331, §1, 3º). The various elements of the penalty underline the fact that the party in question has broken communion with the Church. The prohibition of receiving the sacraments or sacramentals is suspended when the party under sanction is in danger of death, given that he is otherwise properly disposed (cf. can. 1352, §1).
The ordained priest who goes into schism, in addition to being bound by the above-listed prohibitions, is also rendered irregular for the exercise of Holy Orders (cf. can. 1044, §1, 2º). In other words, he may not exercise the Sacrament of Holy Orders which he has received. Any Mass celebrated by a suspended and excommunicated priest is valid, but illicit. To knowingly and willingly celebrate the Holy Mass, when one is legitimately prohibited from doing so, is a most grave sin. A priest under the penalty of excommunication does not give valid sacramental absolution (cf. can. 966, §1). Neither can he validly officiate at a wedding (cf. can. 1108, §1).
The faithful who approach a schismatic priest for the reception of the sacraments, except in the case of danger of death, commit a mortal sin.