Editing Russian Orthodox Church (section)

===Kievan Rus'===
{{see also|Christianization of Kievan Rus'}}

In the 10th century, Christianity began to take root in [[Kievan Rus']].{{sfn|Fennell|2014|page=25}} Towards the end of the reign of [[Igor of Kiev|Igor]], Christians are mentioned among the [[Varangians]].{{sfn|Fennell|2014|page=24}} In the text about the treaty with the [[Byzantine Empire]] in 944–945, the chronicler also records the oath-taking ceremony that took place in [[Constantinople]] for Igor's envoys as well as the equivalent ceremony that took place in Kiev.{{sfn|Fennell|2014|page=25}} Igor's wife [[Olga of Kiev|Olga]] was baptized sometime in the mid-10th century; however, scholars have disputed the exact year and place of her conversion, with dates ranging from 946 to 960.{{sfn|Fennell|2014|page=26|loc=Not that anyone doubts that she was baptized. All are agreed on that. But when, where and under what circumstances? These are the questions that divide the academics}} Most scholars tend to agree that she was baptized in Constantinople, though some argue that her conversion took place in Kiev.{{sfn|Fennell|2014|page=26}} Olga's son [[Sviatoslav I of Kiev|Sviatoslav]] opposed conversion, despite persuasion from his mother,{{sfn|Fennell|2014|page=25}} and there is little information about Christianity in sources in the period between 969 and 988.{{sfn|Fennell|2014|page=31}}

Ten years after seizing power, Grand Prince [[Vladimir the Great|Vladimir]] was baptized in 988 and began [[Christianization of Kievan Rus'|Christianizing his people]] upon his return.{{sfn|Fennell|2014|page=35}} That year was decreed by the Russian Orthodox Church in 1988 as the date of the Christianization of the country.{{sfn|Fennell|2014|page=35}} According to the ''Chronicle'', Vladimir had previously sent envoys to investigate the different faiths.{{sfn|Fennell|2014|page=35}} After receiving glowing reports about Constantinople,{{sfn|Fennell|2014|page=35}} he captured Chersonesus in Crimea and demanded that the sister of [[Basil II]] be sent there.{{sfn|Fennell|2014|page=37}} The marriage took place on the condition that Vladimir would be also baptized there.{{sfn|Fennell|2014|page=37}} Vladimir had lent considerable military support to the Byzantine emperor and may have besieged the city due to it having sided with the rebellious [[Bardas Phokas the Younger|Bardas Phokas]].{{sfn|Fennell|2014|page=37}} By the early 11th century, Christianity was established as the state religion.{{sfn|Kent|2021|p=12}} By the early 13th century, some 40 episcopal sees had been established, all of which ultimately answered to Constantinople.{{sfn|Kent|2021|p=15}}