The ongoing debates about the nature of Christ caused controversy within the Christian Church for centuries.
During the 5th century, some regions of the Christian Church were thrown into confusion because of the debates that erupted over the nature of Jesus Christ. Although the Church had already determined that Christ is the son of God, just what his exact nature is remained open to debate. The Church had declared heretical the notion that Jesus is not fully divine in the 4th century (see First Council of Nicaea), during the debates over Arianism and had declared that he is God the Son become human. However, in arguing that he is both God and man, there now emerged a dispute over exactly how the human and divine natures of Christ actually exist within the person of Christ.
The Christological definition of Chalcedon, as accepted by the Eastern Orthodox, Catholic, Anglican, Lutheran, and Reformed churches, is that Christ remains in two distinct natures, yet these two natures come together within his one hypostasis. More simply, Christ is known as "both fully human and fully Divine, one in being with the Father". This position was opposed by the Monophysites who held that Christ possesses one nature only. The term Monophysitism of which Eutychianism is one type, held that the human and divine natures of Christ were fused into one new single (mono-) nature. As described by Eutyches, his human nature was "dissolved like a drop of honey in the sea", and therefore his nature is really divine. This is distinct from Miaphysitism, which holds that, after the union, Christ is in one theanthropic (human-divine) nature and is generated from the union of two natures. The two are thus united without separation, without confusion, and without alteration, and with each having a particularity. Miaphysitism is the christological doctrine of the Oriental Orthodox churches.
Nevertheless, the resultant debates led the Chalcedonians to accuse the non-Chalcedonians of teaching Christ's humanity to be of a different kind from our own. Meanwhile, the non-Chalcedonians accused the Chalcedonians of espousing a form of Nestorianism, a rejected doctrine that held that Jesus Christ was two distinct subsistences.
This internal division was dangerous for the Byzantine Empire, which was under constant threat from external enemies, especially as many of the areas most likely to be lost to the empire were the regions that were in favour of Monophysitism, and who considered the religious hierarchy at Constantinople to be heretics only interested in crushing their faith. In these provinces, the non-Chalcedonians were far more numerous than the Chalcedonians. In Egypt for instance, some 30,000 Greeks of Chalcedonian persuasion were ranged against some five million Coptic non-Chalcedonians. Meanwhile, Syria and Mesopotamia were divided between Nestorianism and Jacobitism, while the religion of Armenia was wholly Cyrilline Non-Chalcedonian. Consequently, the Monothelite teaching emerged as a compromise position. The Byzantine emperor Heraclius tried to unite all of the various factions within the empire with this new formula that was more inclusive and more elastic.
This approach was needed to win over the non-Chalcedonians, since they, already believing Christ possesses a single nature, necessarily also believed that he holds a single will. But it was unclear whether the Chalcedonians should believe in Christ's human and divine energy and/or will as well as his human and divine nature, because the ecumenical councils had made no ruling on this subject. A ruling in favour of this new doctrine would provide common ground for the non-Chalcedonians and the Chalcedonians to come together, as the non-Chalcedonians could agree that Jesus has two natures if he only had one will, and some Chalcedonians could agree that Jesus has one will if he has two natures.