An Orthodox Response

Pope Honorius, who was pope from 625-638, was anathematized for the heresy of Monothelitism (Jesus only has one will) by both the Sixth and the Eighth Ecumenical Councils. Both the Orthodox Church and the Roman Catholic Church recognize the Sixth council, but only the Roman Catholic Church recognizes the Eighth council. Pope Honorius was also declared to be a heretic in the oath that popes had to take from the 8th to the 11th centuries upon being enthroned to the papacy.

The obvious question is, why would two ecumenical councils and the papal oath declare Honorius to be a heretic, if the church always considered the Roman Catholic Pope to be infallible?

Third Council of Constantinople (680-681)

Exposition of Faith
This pious and orthodox creed of the divine favour was enough for a complete knowledge of the orthodox faith and a complete assurance therein. But since from the first, the contriver of evil did not rest, finding an accomplice in the serpent and through him bringing upon human nature the poisoned dart of death, so too now he has found instruments suited to his own purpose–namely Theodore, who was bishop of Pharan, Sergius, Pyrrhus, Paul and Peter, who were bishops of this imperial city, and further Honorius, who was pope of elder Rome, Cyrus, who held the see of Alexandria, and Macarius, who was recently bishop of Antioch, and his disciple Stephen — and has not been idle in raising through them obstacles of error against the full body of the church sowing with novel speech among the orthodox people the heresy of a single will and a single principle of action in the two natures of the one member of the holy Trinity Christ our true God, a heresy in harmony with the evil belief, ruinous to the mind, of the impious Apollinarius, Severus and Themistius, and one intent on removing the perfection of the becoming man of the same one lord Jesus Christ our God, through a certain guileful device, leading from there to the blasphemous conclusion that his rationally animate flesh is without a will and a principle of action.

Fourth Council of Constantinople (869-870)

Further, we accept the sixth, holy and universal synod {6 Constantinople III}, which shares the same beliefs and is in harmony with the previously mentioned synods in that it wisely laid down that in the two natures of the one Christ there are, as a consequence, two principles of action and the same number of wills. So, we anathematize Theodore who was bishop of Pharan, Sergius, Pyrrhus, Paul and Peter, the unholy prelates of the church of Constantinople, and with these, Honorius of Rome, Cyrus of Alexandria as well as Macarius of Antioch and his disciple Stephen, who followed the false teachings of the unholy heresiarchs Apollinarius, Eutyches and Severus and proclaimed that the flesh of God, while being animated by a rational and intellectual soul, was without a principle of action and without a will, they themselves being impaired in their senses and truly without reason. For if the one and same Christ and God exists as perfect God and perfect man, it is most certain that none of the natures which belong to him can exist partially without a will or without a principle of action, but that he carried out the mystery of his stewardship when willing and acting in accordance with each substance; this is how the chorus of all God’s spokesmen, having knowledge of it from the apostles down to our own time, have constructed a colourful representation of that human form, assigning to each part of the one Christ natural properties distinct from each other, by which the meanings and conceptions of his divine nature and of his human nature are believed beyond all doubt to remain without confusion.

Liber Diurnus

According to the Catholic Encyclopedia the Liber Diurnus Romanorum Pontificum is:

A miscellaneous collection of ecclesiastical formularies used in the papal chancery until the eleventh century. It contains models of the important official documents usually prepared by the chancery; particularly of letters and official documents in connexion with the death, the election, and the consecration of the pope; the installation of newly elected bishops, especially of the suburbicarian bishops; also models for the profession of faith, the conferring of the pallium on archbishops, for the granting of privileges and dispensations, the founding of monasteries, the confirmation of acts by which the Church acquired property, the establishment of private chapels, and in general for all the many decrees called for by the extensive papal administration.

The Catholic Encyclopedia says this about Formula 84 of the Liber Diurnus:

Lucas Holstenius was the first who undertook to edit the Liber Diurnus. He had found one manuscript of it in the monastery of Santa Croce in Gerusalemme at Rome, and obtained another from the Jesuit Collège de Clermont at Paris; but as Holstenius died in the meantime and his notes could not be found, this edition printed at Rome in 1650 was withheld from publication, by advice of the ecclesiastical censors, and the copies put away in a room at the Vatican. The reason for so doing was apparently formula lxxxiv, which contained the profession of faith of the newly elected pope, in which the latter recognized the Sixth General Council and its anathemas against Pope Honorius for his (alleged) Monothelism.

The relevant paragraph of Formula 84, as translated by a friend of mine, says the following:

The authors were in actuality defending the new heretical doctrines of Sergius, Phyrrhus, Paulus, and Petrus of Constantinople, and were in agreement with Honorius, who expanded his perverse fix for the problem.

In listing Pope Honorius in with other heretics that newly elected Popes had to denounce upon their elevation to the throne of St. Peter, the Liber Diurnus shows that the Roman Catholic Church, at least until the 11th century, did not see its Popes as infallible.

— Gary Cattell