He ensured the independence of the Moscow church against the Byzantine church.
(1293 – 1378) Russian cleric. As the third metropolitan of Moscow, he started the efforts to ensure the independence of the Moscow Church against the Byzantine and Roman churches. He was born in Moscow and died there. He was baptized as Elevferiya; When he retired from worldly affairs at a very young age, he took the name Aleksey. He gained great fame in a short time because of his work in the field of religion and his remarkable achievements. It attracted the attention of state elders; especially around the palace, it prevented years of strife for the throne between the princes. Because of this effective behavior, he became the third metropolitan of Moscow; joined the saints.
St. Alexis, Russian Aleksey or Aleksei, (born c. 1295, Moscow, Russia—died 1378, Moscow; canonized 1448; feast day October 5), metropolitan of Moscow from 1354 to 1378 and the first representative of the Russian Orthodox Church to take a truly active role in governing Russia.
According to a rumor in the written sources, when the blind daughter of the Altınordu Khan opened her eyes, she gained great respect and love among the Tatars, took advantage of this situation by considering the interests of the Russian people, and indirectly participated in administrative affairs. In particular, the fact that Tatars lived under Russian rule was effective in not revolting.
He is the first Russian clergyman who started the efforts to ensure the independence of the Moscow Church against the Byzantine and Roman churches and later turned this into a church policy. It enabled the Russian tsars to consider the influence of religion in international relations by collaborating with the church elders and the Moscow Church to emerge as the protector of Byzantium.
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Saint Alexis, Metropolitan of Moscow, Wonderworker of All Russia
https://www.oca.org/saints/lives/2020/02/12/100506-saint-alexis-metropolitan-of-moscow-wonderworker-of-all-russia