We are all obligated to defend the Church and faith.
Saint Photius said: "It is incumbent upon everyone to observe the letter of all that is common to all, and, above all, the points touching the Faith, where to deviate a little is to commit a sin unto death.”
Saint Theodore the Studite:
“Not only if one possesses rank or knowledge is one obliged to strive to speak and to teach the doctrines of Orthodoxy, but even if one be a disciple in rank, one is obliged to speak the truth boldly and openly.”
Saint Theodore the Studite:
“It is a commandment of the Lord that we should not be silent when the Faith is in peril. So, when it is a matter of the Faith, one cannot say, ‘Who am I? A priest, a ruler, a soldier, a farmer, a poor man? I have no say or concern in this matter.’ Alas! The stones shall cry out, and you remain silent and unconcerned?”
"We have a command from the very Apostle himself that says, whoever dogmatizes, or orders you to do something that is against that which we have received, against that which the Canons of the varied in time holy, general and local synods, let us not accept him, nor consider him Orthodox, and I avoid saying the severe word that the Apostle said..., that is let him be anathema "* Theodore the Studite
When talking about heresy, Saint Gregory of Nyssa said: "“better is a laudable war than a peace which severs a man from God.” “For disagreement over piety is better than emotional concord.”
St. Gregory the Theologian, “By your silence you can betray God”.
St. Theodosius of the Kiev Caves: “Live in peace not only with your friends but with your enemies; but only with your personal enemies and not with the enemies of God.”
St. Theodosius of the Kiev Caves (one of the greatest saints) said:
“Beware, my son, of heretics and all their talking, for our land too, has become filled with them! If anyone will save his soul, it will be only through life in the Orthodox Faith. For there is no better faith, than our Holy Orthodox Faith. My son, it is not meet to praise another’s faith. Whoever praises an alien faith is like a detractor of his own Orthodox Faith. If anyone should praise his own and another’s faith, then he is a man of dual faith and is close to heresy. If anyone should say to you: “your faith and our faith is from God”, you, my son, should reply: “Heretic! do you consider God to be of two faiths? Don’t you hear what the Scriptures say: “One Lord, one Faith, one Baptism” (Eph. 4,5). Thus, my son, beware of such people and always stand up for your Faith. Do not fraternize with them, but avoid them and pursue your own Faith with good deeds!” “My son, even if there would be the need for you to die for your holy Faith, dare to embrace death! Thus the Saints died for their Faith, and now they are alive in Christ.”
St. John Chrysostom: “in worldly matters we are meek as lambs, but in matters of the faith we roar like lions!”
Saint Ignatius: "If thy bishop should teach any thing outside of the appointed order, even if he lives in chastity, or if he work signs, or if he prophecy, let him be unto thee as a wolf in sheep's clothing, for he works the destruction of souls."
Saint Felix III of Rome: "An error which is not resisted is approved: a truth which is not defended is suppressed...He who does not oppose an evident crime is open to the suspicion of secret complicity."
Saint Vincent of Lerins:"for Christians to declare something which they did not previously accept has never been permitted, is never permitted, and never will be permitted,—but to anathematize those who proclaim something outside of that which was accepted once and for ever, has always been a duty, is always a duty, and always will be a duty."
Father Georges Florovsky: "Very often the measure of truth is the witness of the minority. It may happen that the Catholic Church will find itself but "a little flock."
Khomiakov's comment: The pope is greatly mistaken in supposing that we consider the ecclesiastical hierarchy to be the guardian of dogma. The case is quite different. The unvarying constancy and the unerring truth of Christian dogma does not depend upon any hierarchical order; it is guarded by the totality, by the whole people of the Church, which is the Body of Christ. As Archimandrite Adrianos, a former abbot of St. Catherine's Monastery on Mount Sinai, notes in this regard: A decision of the Orthodox Church is never imposed from above, as it is by papism: the people of God are the defenders of the faith, wielding a veto, rejecting whatever is contrary to Tradition, and even judging the Orthodoxy of any ecumenical synod that can be characterized as a “robber synod.
Father Georges Florovsky: The whole body of the Church has the right of verifying, or, to be more exact, the right, and not only the right but the duty, of certifying. It was in this sense that in the well known Encyclical Letter of 1848 the Eastern Patriarchs wrote that "the people itself", i.e, the Body of the Church, "was the guardian of piety."
Father Georges:......"therefore in questions of faith the people must judge concerning his teaching. The duty of obedience ceases when the bishop deviates from the catholic norm, and the people have the right to accuse and even to depose him."
Timothy Ware: Yet if Cyril was intemperate in his methods, it was because of his consuming desire that the right cause should triumph; and if Christians were at times acrimonious, it was because they cared about the Christian faith. Perhaps disorder is better than apathy.
The Serbian Canonist Bishop Nikodim Milaa, "every episcopal act is invalid and nothing and no one is required to heed it if it is contrary to the Canons; if it contains something that the Canons do not include; if it does not express whatever the Local Synods have determined and have been proclaimed as institutions; and lastly, if they are in opposition to civil laws that are not contrary to the spirit of the Church."
Archbishop Theophan of Poltava: "you may be subject to God’s judgement if you are indifferent to deviation from the truth: ‘So then because thou art lukewarm, and neither cold not hot, I will spew thee out of My mouth’ (Revelation 3.6).
Archbishop Theophan writes in reply to the question “Can one have a negative feeling in relation to the enemies of the Russian people and the Orthodox Church or must one suppress in oneself this feeling, repeating the words: ‘Vengeance is Mine, I will repay’?”: “To have a negative feeling towards the enemies of God and of the Russian people is natural. And on the contrary not to have a negative feeling is unnatural. Only this feeling must be correct. And it will be correct when it has a principled, not personal character, that is, when we 'hate' the enemies of God and of the Russian people not for their personal offences against us, but for their hostile attitude towards God and the Church and for their inhuman attitude towards Russian people. Therefore it is also necessary to fight with these enemies. Whereas if we do not fight, we will be punished by God for our lukewarmness. He will then take His vengeance not only on them, but also on us..."
Vladimir Moss: "We are not permitted to recognize a bishop until he has shown himself completely Orthodox in word and deed."
Saint Metropolitan Philaret: “Let us remember that this indifference to the truth is one of the main woes of our age of apostasies. Value the truth, O man! Be a fighter for the truth… Place the truth higher than all else in life, O man, and never allow yourself to decline in any way from the true path…”
The Abbot Saint Joseph of Volotsk, was not afraid to expose the Metropolitan of All Russia who turned out to be a heretic.
Ivan Vishenskii OF Mt. Athos defended the right of Christians to depose and drive out apostate bishops.