Monotheletism is the belief that Christ only possesses one will in contrast to dyotheletism which affirms that Christ has two wills: one divine and one human since he is both God and man. Monotheletism was the second attempt at a compromise between orthodoxy and monophysitism in order to reunite the church after monoenergism, the belief that Christ possesses only one energy, activity, or operation, failed. In monotheletism, the divine will of Christ takes the place of his human will. The unintended result of this is that Jesus is less than fully human since he does not have a human will in the same way we do (Heb 2:17). By depriving Jesus of a human will, monotheletism falls into the same error as monophysitism by presenting us with a savior who is less than fully human. Monotheletism and monophysitism are wrong, not just because they fail to take into consideration all of Scripture, but also because they tend toward docetism.
This belief was promoted by Sergius, Patriarch of Constantinople, and Honorius, Bishop of Rome. Honorius wrote to Sergius:
“Wherefore we acknowledge one will of our Lord Jesus Christ, for evidently it was our nature and not the sin in it which was assumed by the Godhead, that is to say, the nature which was created before sin, not the nature which was vitiated by sin”
Both Sergius and Honorius were condemned for teaching monotheletism at the Third Council of Constantinople or Sixth Ecumenical Council in 681:
“After we had reconsidered, according to our 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 Phasis 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. . . . 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 13).
“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, Paul and Peter, who were Archbishops of this royal city, and moreover, Honorius who was Pope of the elder Rome, Cyrus Bishop of Alexandria, Macarius who was lately bishop of Antioch, and Stephen his disciple), 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, a heresy similar to the mad and wicked doctrine of the impious Apollinaris, Severus, and Themistius, and endeavoring craftily to destroy the perfection of the incarnation of the same our Lord Jesus Christ, our God, by blasphemously representing his flesh endowed with a rational soul as devoid of will or operation” (Session 18).