If there be a Christian who has part in the Church of the Seven Ecumenical Councils, or the Church of the Holy Apostles of Jesus Christ, then let him know he is forbidden to pray together with any man of any other faith.
1. Canon 10 of the Holy Apostles: "If one who is not in communion prays together, even at home, let him be excommunicated”
2. Canon 11 of the Holy Apostles: "If one who is a priest prays together with a defrocked priest, let him too be defrocked.”
3. Canon 45 of the Holy Apostles: "A Bishop, or a Presbyter, or a Deacon that only prays together with heretics, should be excommunicated; if he has permitted them to perform anything as Clergymen, let him be defrocked.”
4. Canon 64 of the Holy Apostles: "If a Clergyman or a Layman should enter a Jewish synagogue, or pray with heretics, let him be excommunicated and defrocked.”
5. Canon 71 of the Holy Apostles: "If a Christian should bring oil to a Gentile altar, or to a Jewish synagogue during their feast-days, or light lamps, let him be excommunicated”
6. Canon 6 of the Local Synod of Laodicea: "On the matter of not allowing heretics to enter the house of God, who persist in their heresy"
7. Canon 9 of the Local Synod of Laodicea: "On the matter of not allowing those who are of the Church to go to the cemeteries or to the so-called places of martyrdom of all who are heretics, on the pretext of a blessing or a cure; if they are of the faithful, let them be excommunicated for a certain time, and, after repenting and confessing that they erred, be re-admitted.”
8. Canon 32 of the Local Synod of Laodicea: "That it is not permitted to accept the blessings of heretics, which are foolishness rather than blessings”
9. Canon 33 of the Local Synod of Laodicea: "That one must not pray together with heretics or schismatics”
10. Canon 34 of the Local Synod of Laodicea:. “That it is not proper for any Christian to abandon the witnesses of Christ and go to the false witnesses, that is to say the heretics, or to those who are predisposed to becoming heretics. For they are alien to God. Let them therefore be anathema, who would depart for their sake.”
11. Canon 37 of the Local Synod of Laodicea:. "One must not accept the festive tokens sent by Jews or heretics, nor celebrate together with them."
12. Canon 9 of Timothy of Alexandria: "Question. May a Clergyman offer prayers in the presence of Arians or other heretics? Or does this not harm him in any way, whenever he performs the benediction, that is, the offering?; Reply. During the divine anaphora, the Deacon recites this address prior to the greeting: "Those not in communion, walk away”. Therefore, they do not need to be present, unless they have reported their intention to repent and abandon the heresy"
To the above Canons, one must also add the following:
13. Canon B’ of the Antioch Synod: "All those entering the Church and listening to the divine Scriptures, but not participating in the prayer together with the people, or displaying aversion to the Holy Communion of the Eucharist as an act of disorderliness, let them be cast out of the Church, until they have confessed and have shown works of repentance and are able to beseech forgiveness, thereafter not intending to be in communion with the excommunicated, nor congregate in houses with those who do not pray together in Church, nor with those who do not congregate. Should any of the bishops, or presbyters, or deacons, or someone of the Canon be seen in communion with the excommunicated, let them also be excommunicated, as ones who have confused the Canon of the Church.”
14. Canon A’ of the 4th Ecumenical Synod, (which validates the Canons of the Local Synods of Laodicea and Antioch, and of Saint Timothy of Alexandria)
15. Canon B’ of the 6th Ecumenical Synod, (which validates the Apostolic Canons, the Canons of the Local Synods of Laodicea and Antioch, and of Saint Timothy of Alexandria).
16. Canon A’ of the 7th Ecumenical Synod , (which validates the Apostolic Canons, the Canons of the Local Synods of Laodicea and Antioch, and of Saint Timothy of Alexandria).