"Let not the Symbol of Faith be set aside…but let it remain unchanged: and let every heresy be given over to anathema…"
First Canon of the Second Ecumenical Council
"Let no one be permitted to bring forward, or write or compose a different faith besides that defined by the holy Fathers who assembled with the Holy Spirit in the city of Nicaea. And whoever dares to compose a different faith, or present, or offer [one] to those wishing to turn to the knowledge of the truth…let such, if they be bishops or belong to the clergy, be alien bishops from the episcopate, and clerics from the clergy and if they be laymen, let them be given over to anathema."
Seventh Canon of the Third Ecumenical Council
"We have acknowledged it as just to keep the canons of the holy Fathers set forth at each council till now."
First Canon of the Fourth Ecumenical Council
"…we decree that the faith handed down to us by the eyewitnesses and ministers of the Word, the divinely chosen Apostles, and, further, by the three hundred and eighteen holy and blessed Fathers…who assembled in Nicaea, be preserved inviolate from innovations and changes… Likewise, we also maintain the confession of faith proclaimed by the one hundred and fifty holy Fathers, who assembled in this reigning city under the great Theodosius, our emperor… Likewise, we also seal…the teaching set forth by the two hundred Godbearing Fathers, who assembled the first time in the city of Ephesus under Theodosius, our emperor, the son of Arcadius…
Likewise, we also confirm in Orthodox manner the confession of faith inscribed by the six hundred and thirty divinelychosen Fathers in the provincial city of Chalcedon under Marcian, our emperor… And further, we also recognize as uttered by the Holy Spirit the pious utterances of the one hundred and sixtyfive Godbearing Fathers, who assembled in this reigning city under Justinian, our emperor of blessed memory, and we teach them to our posterity… And we bind ourselves anew to preserve inviolably…the confession of faith of the Sixth Council that came together recently under our emperor,
Constantine of blessed memory, in this reigning city... Speaking briefly, we enact that the faith of all of the men who have been glorified in the Church of God...be keep steadfastly, and that it abide until the end of the age unshaken, together with their divinely handed down writings and dogmas... If anyone at all does not maintain and accept the aforementioned dogmas of piety, and does not think and preach so, but attempts to go against them: let him be anathema, according to the decree previously enacted by the aforementioned holy and blessed Fathers, and let him be excluded and expelled from the Christian estate as an alien."
First Canon of the Sixth Ecumenical Council, in Trullo
For those who have received the priestly dignity, the inscribed canons and enactments serve as testimonies and directions, which we, gladly receiving, sing together with the divinely inspired David unto the Lord, saying: In the way of Thy testimonies have I found delight, as much as in all riches (Psalm 118:14). Likewise, Thou hast ordained as Thy testimonies... righteousness for ever; give me understanding and I shall live (Psalm 118:138, 144). And if the prophetic voice commands us to preserve the testimonies of God for ever, and to live in them, then it is manifest that they abide indestructible and unshakeable. For Moses the Godseer also speaks thus: It is not fitting to add to them, nor is it fitting to take away from them (Deuteronomy 12:32). And the divine Apostle Peter, boasting in them, cries: which things the angels desire to look into (I Peter 1:12). Likewise the Apostle Paul also says: But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed [literally, let him be anathema] (Galatians 1:8). Inasmuch as this is true, and attested unto us, rejoicing over this, as one that has found great spoil, we receive the divine canons with delight, and we maintain wholly and unshakably the enactment of these canons set forth by the allpraised Apostles, the holy trumpets of the Spirit, and by the six holy Ecumenical Councils, and those assembled locally to issue such commandments, and by our holy Fathers. For they all, being enlightened by one and the same Spirit, ordained what is beneficial. And whomever they give over to anathema, those we also anathematize; and whomever to expulsion, those we also expel, and whomever to excommunication, those we also excommunicate; and whomever they subject to penances, those we likewise subject."
First Canon of the Seventh Ecumenical Council