There have been seven Ecumenical Councils in the true Orthodox Christian Church:
5. the second at Constantinople;
6. the third at Constantinople;
7. the second at Nicea.
The First Ecumenical Council
The First Ecumenical Council was convened in 325 A.D., in the city of Nicea, under the Emperor Constantine I. This Council was called because of the false doctrine of the Alexandrian priest Arius, who rejected the Divine nature and pre-eternal birth of the second person of the Holy Trinity, namely the Divine Son of God the Father, and taught that the Son of God is only the highest creation.
318 bishops participated in this Council, among whom were St. Nicholas the Wonderworker, St. James, bishop of Nisibis, St. Spiridon of Tremithus, and St. Athanasius, who was at that time a deacon.
The Council condemned and repudiated the heresy of Arius and affirmed the immutable truth, the dogma that the Son of God is true God, born of God the Father before all ages, and is eternal, as is God the Father; He was begotten, and not made, and is of one essence with God the Father. In order that all Orthodox Christians may know exactly the true teaching of the faith, it was clearly and concisely summarized in the first of seven sections of the Creed, or Symbol of Faith.
At this Council, it was resolved to celebrate Pascha on the first Sunday after the first full moon following the spring equinox, after the Jewish Passover. It also determined that priests should be married, and it established many other rules or canons.
The Second Ecumenical Council
The Second Ecumenical Council was convened in the year 381, in the city of Constantinople, under the Emperor Theodosius I. This Council was convoked against the false teaching of the Arian bishop of Constantinople, Macedonius, who rejected the deity of the third Person of the Holy Trinity, the Holy Spirit. He taught that the Holy Spirit is not God, and called Him a creature, or a created power, and therefore subservient to God the Father and God the Son, like an angel.
There were 150 bishops present at the Council, among whom were Gregory the Theologian, who presided over the Council, Gregory of Nyssa, Meletius of Antioch, Amphilochius of Iconium and Cyril of Jerusalem.
At the Council, the Macedonian heresy was condemned and repudiated. The Council affirmed as a dogma the equality and the single essence of God the Holy Spirit with God the Father and God the Son.
The Council also supplemented the Nicene Creed, or “Symbol of Faith,” with five Articles in which is set forth its teaching about the Holy Spirit, about the Church, about the Mysteries, about the resurrection of the dead, and the life in the world to come. Thus they composed the Nicene-Constantinopolitan Creed, which serves as a guide to the Church for all time.
The Third Ecumenical Council
The Third Ecumenical Council was convened in the year 431 A.D., in the city of Ephesus, under Emperor Theodosius II. The Council was called because of the false doctrine of Nestorius, Archbishop of Constantinople, who profanely taught that the Most-holy Virgin Mary simply gave birth to the man Christ, with whom then God united morally and dwelled in Him, as in a temple, as previously He had dwelled in Moses and other prophets. Therefore, Nestorius called the Lord Jesus Christ, God-bearing, and not God incarnate; and the Holy Virgin was called the Christ-bearer (Christotokos) and not the God-bearer (Theotokos).
The 200 bishops present at the Council condemned and repudiated the heresy of Nestorius and decreed that one should recognize that united in Jesus Christ at the time of the incarnation were two natures, divine and human, and that one should confess Jesus Christ as true God and true Man, and the Holy Virgin Mary as the God-bearer (Theotokos).
The Council also affirmed the Nicene-Constantinopolitan Creed, and strictly prohibited making any changes or additions to it.
The Fourth Ecumenical Council
The Fourth Ecumenical Council was convened in 451 A.D., in the city of Chalcedon, under Emperor Marcian. The Council met to challenge the false doctrine of an archimandrite of a Constantinople monastery, Eu-tychius, who rejected the human nature of the Lord Jesus Christ. Refuting one heresy and defending the divinity of Jesus Christ, he himself fell into an extreme, and taught that in the Lord Jesus Christ human nature was completely absorbed in the Divine, and therefore it followed that one need only recognize the Divine nature. This false doctrine is called Monophysitism, and followers of it are called Monophysites.
The Council of 650 bishops condemned and repudiated the false doctrine of Eutychius and defined the true teaching of the Church, namely that our Lord Jesus Christ is perfect God, and as God He is eternally born from God. As man, He was born of the Holy Virgin and in every way is like us, except in sin. Through the incarnation, birth from the Holy Virgin, divinity and humanity are united in Him as a single Person, infused and immutable, thus reputing Eutychius; indivisible and inseparable, reputing Nestorius.
The Fifth Ecumenical Council
The Fifth Ecumenical Council was convened in 553 A.D., in the city of Constantinople, under the famous Emperor, Justinian I. It was called to quell a controversy between Nestorians and Eutychians. The major points of contention were the well-known works of the Antiochian school of the Syrian church, entitled “The Three Chapters.” Theodore of Mopsuestia, Theodoret of Cyrus, and Ibas of Edessa, clearly expressed the Nestorian error, although at the Fourth Ecumenical Council, nothing had been mentioned of their works.
Nestorians, in argument with Eutychians (Monophysites), referred to these works, and Eutychians found in them an excuse to reject the Fourth Ecumenical Council and to slander the universal Orthodox Church, charging that it was deviating toward Nestorianism.
The Council was attended by 165 bishops, who condemned all three works and Theodore of Mopsuestia himself, as not having repented. Concerning the other two, censure was limited only to their Nestorian works. They themselves were pardoned. They renounced their false opinions and died in peace with the Church. The Council reiterated its censure of the heresies of Nestorius and Eutychius.
The Sixth Ecumenical Council
The Sixth Ecumenical Council was convened in the year 680 A.D., in the city of Constantinople, under the Emperor Constantine IV, and was composed of 170 bishops.
The council was convoked against the false doctrine of heretics, Monothelites, who, although they recognized in Jesus Christ two natures, God and man, ascribed to Him only a Divine will.
After the Fifth Ecumenical Council, agitation provoked by the Monothelites continued and threatened the Greek Emperor with great danger. Emperor Heraclius, wishing reconciliation, decided to incline Orthodoxy to concession to the Monothelites, and by the power of his office, ordered recognition that in Jesus Christ is one will and two energies.
Among the defenders and advocates of the true teachings of the Church, were St. Sophronius, Patriarch of Jerusalem, and a monk from Constantinople, St. Maximus the Confessor, who for his firmness in the faith had suffered having his tongue cut out and his hand chopped off.
The Sixth Ecumenical Council condemned and repudiated the heresy of Monothelitism, and formulated the recognition that in Jesus Christ are two natures, Divine and human, and in these two natures there are two wills, but that the human will in Christ is not against, but rather is submissive to His Divine will.
It is worthy of attention that at this Council excommunication was pronounced against a number of other heretics, and also against the Roman Pope Honorius, as one who acknowledged the teaching of one will. The formulation of the Council was signed by a Roman delegation, consisting of Presbyters Theodore and Gregory, and Deacon John. This clearly shows that the highest power in Christendom belongs to the Ecumenical Council, and not to the Pope of Rome. After eleven years, the Council again opened a meeting in the imperial palace, called Cupola Hall (in Greek, Trullos), in order to resolve questions of primary importance pertaining to the Church hierarchy. In this regard, it supplemented the Fifth and Sixth Ecumenical Councils, and therefore is called the Fifth-Sixth (Quintsext) Synod.
This Council established canons by which the Church must be guided, namely, 85 canons of the holy Apostles, canons of the six Ecumenical and seven local councils, and canons of thirteen Fathers of the Church. These canons afterward were supplemented by canons of the Seventh Ecumenical Council and another two local councils, and comprise the so-called “Nomocanon,” in English, “The Rudder,” which is the foundation of Orthodox Church government.
Here several innovations of the Roman Church were condemned as not being in agreement with the spiritual decisions of the Ecumenical Church, namely, the requirement that priests and deacons be celibate, a strict fast on Saturdays of the Great Fast, and the representation of Christ in the form of a lamb, or in any way other than He appeared on the earth.
The Seventh Ecumenical Council
The Seventh Ecumenical Council was convened in 787 A.D., in the city of Nicea, under the Empress Irene, widow of the Emperor Leo IV, and was composed of 367 fathers.
The Council was convened against the iconoclastic heresy, which had been raging for sixty years before the Council, under the Greek Emperor Leo III, who, wishing to convert the Mohammedans to Christianity, considered it necessary to do away with the veneration of icons. This heresy continued under his son, Constantine V Copronymus, and his grandson, Leo IV.
The Council condemned and repudiated the iconoclastic heresy and determined to provide and to put in the holy churches, together with the likeness of the honored and Life-giving Cross of the Lord, holy icons, to honor and render homage to them, elevating the soul and heart to the Lord God, the Mother of God and the Saints, who are represented in these icons. After the Seventh Ecumenical Council, persecution of the holy icons arose anew under the Emperors Leo V, of Armenian origin, Michael II, and Theophilus, and for twenty-five years disturbed the Church.
Veneration of the holy icons was finally restored and affirmed by the local synod of Constantinople in 843 A.D., under the Empress Theodora.
At this council, in thanksgiving to the Lord God for having given the Church victory over the iconoclasts and all heretics, the celebration of the Triumph of Orthodoxy was established on the first Sunday of Great Lent, which is celebrated by the Orthodox Church throughout the world.