First Bulgarian Empire
Bulgarian Orthodox Church

Around 870 the Bulgarian Church became an autonomous archbishopric. The decree of autonomy under the nominal ecclesiastical jurisdiction of Constantinople was far greater than could possibly have been achieved under the Papacy. Following the Fourth Council of Constantinople the Byzantine clergy was re-admitted to Bulgaria and allowed to preach in Greek. However, as a result of the Council of Preslav in 893 Old Bulgarian was declared the official language of the state and the Church and the Greek-speaking Byzantine priests once again had to leave the country. Thus, from that point, the church was entirely staffed by Bulgarians.

Boris I's successor Simeon I was not content to leave the Bulgarian Church as an archbishopric and was determined to raise it to a patriarchate, in light of his own ambition to become an emperor. He was well acquainted with the Byzantine imperial tradition that the autocrat must have a patriarch and there could be no empire without one. In the aftermath of his remarkable triumph over the Byzantines in the battle of Achelous, in 918 he convened a council and elevated Archbishop Leontius to patriarch. The decisions of that council were not recognized by the Byzantines but as a result of the Bulgarian victory in the war they eventually recognized Leontius' successor Demetrius as Patriarch of Bulgaria in 927. It was the first Patriarchate officially accepted, apart from the ancient Pentarchy. It is likely that the seat of the Patriarchate was in the city of Drastar on the Danube River rather than in the capital Preslav. In the late 10th century the Bulgarian Patriarchate included the following dioceses: Ohrid, Kostur, Glavinitsa (in modern southern Albania), Maglen, Pelagonia, Strumitsa, Morovizd (in modern northern Greece), Velbazhd, Serdica, Braničevo, Niš, Belgrade, Srem, Skopje, Prizren, Lipljan, Servia, Drastar, Voden, Ras, Chernik, Himara, Drinopol, Butrint, Yanina, Petra and Stag.

After the fall of the eastern parts of the empire under Byzantine occupation in 971 the seat of the Patriarchate was relocated to Ohrid in the west. With the final conquest of Bulgaria in 1018 the Patriarchate was demoted to an archbishopric but retained many privileges. It kept control of all existing episcopal sees, the seat remained in Ohrid and its titular, the Bulgarian John of Debar, kept his office. Furthermore, the Bulgarian archbishopric was given a special position – it was placed directly under the emperor rather than under the Ecumenical Patriarch of Constantinople.

Monasticism grew steadily and the monasteries quickly became major landowners with a large population of peasants living on their estates. It developed further under the reign of Emperor Peter I, accompanied by the augmentation of their properties. Many high-ranking nobles and members of the ruling family tonsured and died as monks, including Boris I, his brother Doks, Peter I, the ichirgu-boila Mostich, etc. The growing opulence of monastic life led to an increase of asceticism among more pious monks. One of them, John of Rila, became a hermit in the Rila Mountains and his virtues soon attracted a number of followers, who founded the renowned Rila Monastery after his death. He preached about living in harmony and stressed the value of manual labour and the need the monks never to aspire to riches and power. John of Rila was revered as a saint while he was still alive and eventually became patron of the Bulgarian people.

In the 10th century Bulgarian clerics established connections with the emerging Christian communities in the Rus'. Bulgaria seems to had been an established centre from where the small number of Ruthenian Christians obtained clergy and liturgical texts. As a result of the Sviatoslav's invasion of Bulgaria many of his soldiers were influenced by Christianity and maintained that interest after their return. The connections between Bulgarians and Ruthenians must be considered an important background to the official conversion to Christianity of Kievan Rus' in 988.
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