Pope Honorius of Rome was condemned by the sixth ecumenical council for monothelitism. He wrote a letter to Patriarch Sergius who had asked not for a personal opinion as RC authors allege but for confirmation of the teaching of the Church. Honorius responded by teaching monothelitism.
Session XIII: The holy council said: After we had reconsidered, according to the promise which we had made to your highness, the doctrinal letters of Sergius, at one time patriarch of this royal God protected city to Cyrus, who was then bishop of Phasius and to Honorius some time Pope of Old Rome, as well as the letter of the latter to the same Sergius, we find that these documents are quite foreign to the apostolic dogmas, to the declarations of the holy Councils, and to all the accepted Fathers, and that they follow the false teachings of the heretics; therefore we entirely reject them, and execrate them as hurtful to the soul. But the names of those men whose doctrines we execrate must also be thrust forth from the holy Church of God, namely, that of Sergius some time bishop of this God-preserved royal city who was the first to write on this impious doctrine; also that of Cyrus of Alexandria, of Pyrrhus, Paul, and Peter, who died bishops of this God preserved city, and were like minded with them; and that of Theodore sometime bishop of Pharan, all of whom the most holy and thrice blessed Agatho, Pope of Old Rome, in his suggestion to our most pious and God preserved lord and mighty Emperor, rejected, because they were minded contrary to our orthodox faith, all of whom we define are to be subject to anathema. And with these we define that there shall be expelled from the holy Church of God and anathematized Honorius who was some time Pope of Old Rome, because of what we found written by him to Sergius, that in all respects he followed his view and confirmed his impious doctrines.
Session XVI: To Theodore of Pharan, the heretic, anathema! To Sergius, the heretic, anathema! To Cyrus, the heretic, anathema! To Honorius, the heretic, anathema! To Pyrrhus, the heretic, anathema! To Paul, the heretic, anathema!...
Session XVIII: But as the author of evil, who, in the beginning, availed himself of the aid of the serpent, and by it brought the poison of death upon the human race, has not desisted, but in like manner now, having found suitable instruments for working out his will we mean Theodorus, who was bishop of Pharan, Sergius, Pyrrhus...and moreover, Honorius, who was Pope of the elder Rome...), has actively employed them in raising up for the whole Church the stumbling blocks of one will and one operation in the two natures of Christ our true God, one of the Holy Trinity; thus disseminating, in novel terms, amongst the orthodox people, an heresy similar to the mad and wicked doctrine of the impious Apollinaris (Philip Schaff and Henry Wace, Nicene and Post-Nicene Fathers (Grand Rapids: Eerdmans, 1956), Volume XIV, The Seven Ecumenical Councils, pp. 342-344).
Scholars basically echo what this Roman Catholic historian states:
This one fact, that a Great Council, universally received afterwards without hesitation throughout the Church, and presided over by Papal legates, pronounced the dogmatic decision of a Pope heretical, and anathematized him by name as a heretic is a proof, clear as the sun at noonday, that the notion of any peculiar enlightenment or in errancy of the Popes was then utterly unknown to the whole Church (Janus (Johann Joseph Ignaz von Dollinger), The Pope and the Council (Boston: Roberts, 1870), p. 61).
Another very well respected RC historian, Charles Joseph Hefele, confirms this:
It is in the highest degree startling, even scarcely credible, that an Ecumenical Council should punish with anathema a Pope as a heretic!...That, however, the sixth Ecumenical Synod actually condemned Honorius on account of heresy, is clear beyond all doubt, when we consider the following collection of the sentences of the Synod against him:
At the entrance of the thirteenth session, on March 28, 681, the Synod says: "After reading the doctrinal letter of Sergius of Constantinople to Cyrus of Phasis (afterwards of Alexandria) and to Pope Honorius, and also the letter of the latter to Sergius, we found that these documents were quite foreign...to the apostolic doctrines, and to the declarations of the holy Councils and all the Fathers of note, and follow the false doctrines of heretics. Therefore we reject them completely, and abhor...them as hurtful to the soul. But also the names of these men must be thrust out of the Church, namely, that of Sergius, the first who wrote on this impious doctrine. Further, that of Cyrus of Alexandria, of Pyrrhus, Paul, and Peter of Constantinople, and of Theodore of Pharan, all of whom also Pope Agatho rejected in his letter to the Emperor. We punish them all with anathema. But along with them, it is our universal decision that there shall also be shut out from the Church and anathematized the former Pope Honorius of Old Rome, because we found in his letter to Sergius, that in everything he followed his view and confirmed his impious doctrine."
Towards the end of the same session the second letter of Pope Honorius to Sergius was presented for examination, and it was ordered that all the documents brought by George, the keeper of the archives in Constantinople, and among them the two letters of Honorius, should immediately be burnt, as hurtful to the soul.
Again, the sixth Ecumenical Council referred to Honorius in the sixteenth session, on August 9, 681, at the acclamations and exclamations with which the transactions of this day were closed. The bishops exclaimed: "Anathema to the heretic Sergius, to the heretic Cyrus, to the heretic Honorius, to the heretic Pyrrhus"
Still more important is that which took place at the eighteenth and last session, on September 16, 681. In the decree of the faith which was now published, and forms the principal document of the Synod, we read: "The creeds (of the earlier Ecumenical Synods) would have sufficed for knowledge and confirmation of the orthodox faith. Because, however, the originator of all evil still always finds a helping serpent, by which he may diffuse his poison, and therewith finds fit tools for his will, we mean Theodore of Pharan, Sergius, Pyrrhus, Paul, Peter, former bishops of Constantinople, also Honorius, Pope of Old Rome, Cyrus of Alexandria, etc., so he failed not, by them, to cause trouble in the Church by the scattering of the heretical doctrine of one will and one energy of the two natures of the one Christ.
After the papal legates, all the bishops, and the Emperor had received and subscribed this decree of the faith, the Synod published the usual (logos prosphoneticos), which, addressed to the Emperor, says, among other things: "Therefore we punish with exclusion and anathema, Theodore of Pharan, Sergius, Paul, Pyrrhus, and Peter; also Cyrus, and with them Honorius, formerly bishop of Rome, as he followed them."
In the same session the Synod also put forth a letter to Pope Agatho, and says therein: \'91We have destroyed the effort of the heretics, and slain them with anathema, in accordance with the sentence spoken before in your holy letter, namely, Theodore of Pharan, Sergius, Honorius.
In closest connection with the Acts of the sixth Ecumenical Council stands the imperial decree confirming their resolutions. The Emperor writes: "With this sickness (as it came out from Apollinaris, Eutyches, Themistius, etc.) did those unholy priests afterwards again infect the Church, who before our times falsely governed several churches. These are Theodore of Pharan, Sergius the former bishop of this chief city; also Honorius, the Pope of old Rome...the strengthener (confirmer) of the heresy who contradicted himself...We anathematise all heresy from Simon (Magus) to this present...besides, we anathematise and reject the originators and patrons of the false and new doctrines, namely, Theodore of Pharan, Sergius...also Honorius, who was Pope of Old Rome, who in everything agreed with them, went with them, and strengthened the heresy."
It is clear that Pope Leo II also anathematized Honorius...in a letter to the Emperor, confirming the decrees of the sixth Ecumenical Council...in his letter to the Spanish bishops...and in his letter to the Spanish King Ervig. Of the fact that Pope Honorius had been anathematized by the sixth Ecumenical Synod, mention is made by...the Trullan Synod, which was held only twelve years after...Like testimony is also given repeatedly by the seventh Ecumenical Synod; especially does it declare, in its principal document, the decree of the faith: "We declare at once two wills and energies according to the natures in Christ, just as the sixth Synod in Constantinople taught, condemning...Sergius, Honorius, Cyrus, etc." The like is asserted by the Synod or its members in several other places...To the same effect the eighth Ecumenical Synod expresses itself. In the Liber Diurnus the Formulary of the Roman Chancery (from the fifth to the eleventh century), there is found the old formula for the papal oath...according to which every new Pope, on entering upon his office, had to swear that "he recognised the sixth Ecumenical Council, which smote with eternal anathema the originators of the heresy (Monotheletism), Sergius, Pyrrhus, etc., together with Honorius" (Charles Joseph Hefele, A History of the Councils of the Church (Edinburgh: Clark, 1896), Volume V, pp. 181-187).
Was the Ecumenical Council either wrong, or not thorough enough in checking the facts?