Patriarch John (the Faster) assumes the title 'Ecumenical (universal) Patriarch'; which title, in spite of protest by the Roman popes (Pelagius II, and later Gregory I), is later handed down to his successors.

Pope Leo III sends a representative to Constantinople to remove the image of Christ from over the Bronze Gate of the city and replace it with a simple cross. The Roman legate is murdered by a mob and his corpse sent back to Rome clutching the cross he tried to erect.

Patriarch Germanus appeals to Pope Gregory II against Byzantine Emperor Leo's III edict for the destruction of church images which obstruct the conversion of Jews and Muslims. Germanus is deposed, and the Pope condemns Leo's actions.

King Boris I of Bulgaria writes to the Pope Nicholas I with 106 questions, including queries on the impositions of the Orthodox church (Byzantine) in Bulgaria, such as:

Patriarch Photius, in response to Rome's competitive missionary interest in Bulgaria,  calls the Latin missionaries:

Patriarch Michael Cerularius closes Latin churches in Constantinople because they refuse to adopt the Greek rite. He is excommunicated by the Roman church (Pope Leo IX) and in return anathematises the pope's representatives.

Roman Catholic Church legates travel to Patriarch Cerularius to deny him the title Ecumenical Patriarch and to insist that he recognize the Church of Rome's claim to be the head and mother of the churches. Cerularius refuses and the leader of the Latin contingent, Cardinal Humbert, excommunicates Patriarch Cerularius, while Cerularius in return excommunicates Cardinal Humbert and other legates from Rome

Emperor Michael Paleologos is repudiated by the church for submitting to the Pope and accepting the filioque clause ('and the Son') into the creed.

The filioque clause is again repudiated.

Metropolitan of Athens, Michael Choniates, says Latins take longer to appreciate –

The Pope (Eugenius IV) obtains the submission of the eastern emperor at Florence, and consequently the Orthodox Church agrees that –

Acceptance of the Latin Church's filioque clause in the Creed is announced to an apathetic congregation in St. Sophia.

In Jerusalem, Eastern Orthodox (Greek) Patriarch Germanus institutes the Hellenic Confederacy of the Holy Sepulchre as official guardians of the Christian holy places, while the Franciscans (Roman Catholic) form a national community to guard the same holy places on behalf of Latin Christianity.

In Russia – Patriarch Nikon issues his 'Reminder' to the Russian Church which results eventually in a schism of that Church in 1666 concerning how rituals, such as crossing yourself with two fingers or three, making a bow not lower than the waist, and whether the spelling of Jesus in Russian should be 'Easus' or 'Esus'.

The Greek Orthodox buy the right to rebuild the Holy Sepulchre Church.
The Greek Orthodox Church erases all history of a Latin presence at the site, and the graves of King Baldwin I and Godfrey of Bouillon are thrown out.

In Ottoman Palestine – a violent brawl between Roman Catholic and Greek Orthodox clergy in the Nativity Church (Bethlehem) leads to political dispute between France (for the Catholic clergy) and Russia (for the Orthodox clergy) over 'protection' of the holy places.
In the face of Russian demands to exercise supervision over the Orthodox Church subjects of the Ottoman rulers, Britain supports the Ottoman Turks, who had been coerced by France to give Orthodox control of the holy places to the Roman Catholic Church.
War between the parties breaks out in Crimea from 1853-56, costing the lives of about 500,000 men.

In Bucharest – a 23-year-old Romanian Orthodox nun dies after she is tied to a cross in an exorcism ceremony and left in a cold room for three days without food by members of the Holy Trinity convent. They claimed to be "trying to cast out evil spirits".

May 17: Russian Orthodox leaders sign a pact to heal an 80-year schism between the church in Russia and an offshoot set up abroad, which split off in anger when the Russian church declined to defy the Communist government.

In Addis Ababa – Amharic language Ethiopian newspaper 'Addis Neger' is sued by the Ethiopian Orthodox Church, for defaming the church by writing of Patriarch Abune Paulos and the ongoing power struggle inside the church's executive committee. As a result journalist Abraham Begize is arrested and released on bail, after previously being beaten by unidentified men while investigating the crisis in the church's Addis Ababa Diocese.

In Cairo – In response to Egypt's High Administrative Court approving the remarriage of divorced Copts, Coptic Pope Shenouda III (Mohamed Hossam Eddin of Alexandria) declares the decision an attack on their religion for marriage is a religious act of their Church which cannot be dissolved by a secular court decision, and has appealed to the country's president Hosni Mubarak to set aside the court's decision by a presidential decree. The Church asserts that the Bible (as interpretation by them) represents the only frame of reference for Copts.