Christianization of Kievan Rus'

The Christianization of Kievan Rus' was a long and complicated process that took place in several stages. In 867, Patriarch Photius of Constantinople told other Christian patriarchs that the Rus' people were converting enthusiastically, but his efforts seem to have entailed no lasting consequences, since the Russian Primary Chronicle and other Slavonic sources describe the tenth-century Rus' as still firmly entrenched in Slavic paganism.

Source: Wikipedia — Christianization of Kievan Rus' (CC BY-SA 4.0)