Council of Florence in the context of "One true church"

Metropolitan of Kyiv is an episcopal title that has been created with varying suffixes at multiple times in different Christian churches, though always maintaining the name of the metropolitan city — Kiev (Kyiv) — which today is located in the modern state of Ukraine. The church was canonically established and governed by the Ecumenical Patriarch of Constantinople in Kievan Rus'. Following the Council of Florence and the Union of Brest, there are now parallel apostolic successions: in the Russian Orthodox Church, the Orthodox Church of Ukraine, the Ruthenian Uniate Church and its successors. This list contains the names of all the metropolitan bishops (hierarchs) who have claimed the title. It is arranged chronologically and grouped per the claimed jurisdiction.

Georgios Gemistos Plethon (Greek: Γεώργιος Γεμιστὸς Πλήθων; Latin: Georgius Gemistus Pletho c. 1355/1360 – 1452/1454), commonly known as Gemistos Plethon, was a Greek scholar and one of the most renowned philosophers of the Late Byzantine era. He was a chief pioneer of the revival of Greek scholarship in Western Europe. As revealed in his last literary work, the Nomoi or Book of Laws, which he circulated only among close friends, he rejected Christianity in favour of a return to the worship of the classical Hellenic gods, mixed with ancient wisdom based on Zoroaster and the Magi.

In 1438–1439 he reintroduced Plato's ideas to Western Europe during the Council of Florence, in a failed attempt to reconcile the East–West schism. Plethon also formulated his political vision in several speeches throughout his life. The boast in one of the speeches that "We are Hellenes by race and culture" and his proposal of a reborn Byzantine Empire following a utopian Hellenic system of government centered in Mystras, have generated discussion about Byzantine and modern Greek identity. In this regard, Plethon has been labelled both "the last Hellene" and "the first modern Greek".

The Syriac Catholic Church is an Eastern Catholic sui iuris (self-governing) particular church that is in full communion with the Holy See and with the entirety of the Catholic Church. Originating in the Levant, it uses the West Syriac Rite liturgy and has many practices and rites in common with the Syriac Orthodox Church. The Syriac language, a dialect of Aramaic, is the liturgical language used by the Church. There are about 160,000 Syriac Catholics, with the majority in Syria and Iraq, along with a smaller community in Lebanon and an overseas diaspora. It is one of the smaller Eastern Catholic churches based in the Middle East.

The Syriac Catholic Church traces its history and traditions to the Church of Antioch established by Saint Peter. The Diocese of the East under the Patriarch of Antioch included the western Middle East along the Mediterranean. The Church of Antioch was split following the Council of Chalcedon in 451 over disagreements on Christology, with the Syriac, Coptic, and Armenian churches becoming part of Oriental Orthodoxy after rejecting the outcome of the council. A decree of unity between the Syriac Orthodox Church and Rome was made at the Council of Florence in 1444 but it was quickly annulled by the Syriac hierarchy. After missionary work led to conversions to Catholicism among Syriac Christians in the 17th century, one of them, Andrew Akijan, was elected as the Syriac Patriarch of Antioch in 1662. After his death in 1677, rival Catholic and Orthodox Syriac patriarchs were elected between then and 1702. The current line of Syriac Catholic patriarchs of Antioch began in 1782, when Michael Jarweh declared himself in communion with the pope of Rome after being elected by the Syriac Orthodox Holy Synod.

The history of the Russian Orthodox Church begins with the Christianization of Kievan Rus' in 988 during the reign of Vladimir the Great. In the following centuries, Kiev and later other cities, including Novgorod, Pskov, Rostov, Suzdal and Vladimir, became important regional centers of Christian spirituality and culture. Following the Mongol invasions of the 13th century, the seat of the metropolitan was moved to Vladimir in 1299, and then to Moscow in 1325, which would become the spiritual center of Russian Orthodoxy.

The metropolitans of the Russian Church supported the rise of the Moscow principality and his presence increased the Muscovite prince's authority and ambition to unify the lands. In turn, the metropolitans were able to increase the stability of the Church and to inspire unity among the divided Russian principalities. By the mid-15th century, Moscow was both the political and religious center of the country. The Russian Church declared autocephaly in 1448, shortly before the fall of Constantinople, owing to its protest over the Council of Florence. At the behest of the grand prince of Moscow, a council of Russian bishops elected a local bishop without the approval of Constantinople.

Pope Pius II (Latin: Pius PP. II, Italian: Pio II), born Enea Silvio Bartolomeo Piccolomini (Latin: Aeneas Silvius Bartholomeus; 18 October 1405 – 14 August 1464), was head of the Catholic Church and ruler of the Papal States from 19 August 1458 to his death in 1464.

Aeneas Silvius was an author, diplomat, and orator, and private secretary of Antipope Felix V and then the Emperor Frederick III, and then Pope Eugenius IV. He participated in the Council of Basel, but left it in 1443 to follow Frederick, whom he reconciled to the Roman obedience. He became Bishop of Trieste in 1447, Bishop of Siena in 1450, and a cardinal in 1456.

Niccolò Albergati (1373 – 9 May 1443) was an Italian Carthusian and a prelate of the Roman Catholic Church. He was appointed cardinal and served as a papal diplomat to France and England (1422–23) in addition to serving as the bishop of Bologna from 1417 until his death.

He accepted the position as bishop in obedience despite his extreme reluctance to accept the position but carried out his duties with care and attention to educational concerns. But two conflicts in his see caused him to depart and later return and he became known for being close to Pope Martin V and his successor Pope Eugene IV. Both men held Albergati in high esteem and nominated him to crucial positions within the Roman Curia and the diplomatic service to oversee important missions. He had prominent roles in the Council of Basel-Ferrara-Florence and also attended the Council of Florence.

The term Catholic Bible can be understood in two ways. More generally, it can refer to a Christian Bible that includes the whole 73-book canon recognized by the Catholic Church, including some of the deuterocanonical books (and parts of books) of the Old Testament which are in the Greek Septuagint collection, but which are not present in the Hebrew Masoretic Text collection. More specifically, the term can refer to a version or translation of the Bible which is published with the Catholic Church's approval, in accordance with Catholic canon law. The current official version of the Catholic Church is the Nova Vulgata.

According to the Decretum Gelasianum (a work written by an anonymous scholar between AD 519 and 553), Catholic Church officials cited a list of books of scripture presented as having been made canonical at the Council of Rome (382). Later, the Catholic Church formally affirmed its canon of scripture with the Synod of Hippo (393), followed by a Council of Carthage (397), another Council of Carthage (419), the Council of Florence (1431–1449), and the Council of Trent (1545–1563). The canon consists of 46 books in the Old Testament and 27 books in the New Testament, for a total of 73 books in the Catholic Bible.