Nestorius had considered the relation between the two natures of Christ to be so loose that he distinguished in them two separate persons, united only by a moral tie such as is created, for instance, between man and wife by marriage. At the other extreme, Eutychius and Dioscorus held the union to be so close that they taught that, after the Incarnation of the Son and Logos, not two but one single nature should be spoken of; that is, the divine, which had either absorbed the human into itself, or had mingled and fused with it. It was in order to condemn this other extreme of opinion, known as Monophysitism, that the Fourth Ecumenical Synod met at Chalcedon in 451, in the reign of the Empress Pulcheria. This Synod issued a Decree which both reaffirmed the pronouncements of the Third Synod, that the Lord is one and the same, perfect in Godhead as in manhood, and that two natures exist in the God-Man, and also laid it down that these two natures are united in the single Person of the Logos, not only “without distinction and without separation,” but “without confusion and without change” as well, the one nature suffering neither annihilation nor alteration by the other.

The Fifth Ecumenical Synod.

   The decisions of the Synod of Chalcedon were not, however, universally accepted. The Armenians, considering that the Decree of Chalcedon verged on Nestorianism, rejected it at a local Synod which met at Etchmiadzin in 491. The Copts of Egypt, their neighbors the Abyssinians, and the Syrian Jacobites likewise preferred to break away from the Catholic Church and to found schismatic Monophysite communities rather than admit two separate natures in Christ, — a doctrine which they thought amounted to cutting in two the Person of the God-Man and returning to the teaching of Nestorius. In order to emphasize the difference between the recognition of two persons in Christ, which was the heretical opinion held by Nestorius, and the recognition of two natures in one Person, which was the Orthodox teaching of the Holy Catholic and Apostolic Church, the Emperor, Justinian the Great, following the now established custom, convened the Fifth Ecumenical Synod at Constantinople in 553. This Synod condemned certain Theological works of Nestorian flavor, hoping thereby to conciliate the Monophysites and to persuade them to return to the Catholic Church.

The Sixth Ecumenical Synod.

   Another method was followed by the Emperor Heraclius (611-641), who was moved chiefly by political considerations and was striving by every means to maintain the threatened unity of his empire. He tried to reconcile Monophysites and Orthodox on the basis of the formula of “two natures in Christ, but one activity,” or, as a later edict phrased it, “two natures in Christ, but one will.” This solution of the controversy, known under the name of Monotheletism, was not, however, acceptable to the Orthodox theologians, who pronounced it contrary to the Gospel and to sound reasoning. If Christ had two natures, it was inevitable that He should also have had two activities, — as God working miracles, rising from the dead, and ascending into Heaven; as man, performing the ordinary acts of daily life. Similarly, if He had two natures, each one must have Јad its individual will. In 680, therefore, under Constantine Pogonatus, the Sixth Ecumenical Synod was convened at Constantinople. Its members condemned Monotheletism as a heresy, and laid it down that as in Jesus Christ there are two natures, unconfused, unchanged, inseparable and indivisible, so also there are in Him two natural activities and two wills, which do not strive against each other, since the human will subordinates itself to the all-powerful divine will. To this very day one small community still adheres to Monotheletism; it is that of the Maronites of Lebanon.