The Beginnings of Christianity in Kyivan Rus’:
Due to the creation of the Metropolitanate of Kyiv within the Patriarchate of Constantinople in the Late 10th century, Rus’ became part of Christian civilization, Prior to Christianity being officially adopted as the state religion in 988, there were already pockets of Christianity in the territory of the medieval Kyivan state and adjacent areas, though some of them had fallen into decay. There is a widely known tradition that St. Andrew the Apostle blessed the lands of what later became Ukraine. Hem ay have actually reached Greek settlements in today southern Ukraine, but it is unlikely that he travelled further north. There is also a tradition that St. Paul, when preaching in the Balkans, sent his disciple Andronicus, “one of the seventy,” to the Slavs. There is also the witness of the Fathers of the Church, including St. John Chrysostom (d. 407), St. Athanasius the Great (d. 373) and blessed Jerome of Stridon (d. 420), which tell us of the spread of Christianity among the Scythians and Samaritans.
It should also be noted that in the south of present-day Ukraine there were a number of eparchies whose representatives were recorded as members of the Ecumenical Councils in the first millennium. For example, the Bishop of Bosporus participated in the First Council of Nicaea in 325, and in 691-692, Bishop Gregory of Dory (Crimea) participated in the Council of Trullo.
There us evidence that there lived a people known as Rhosses in the same southern Ukrainian region, which was unlikely to have a direct relationship to Rus and was not Slavic. However, Byzantine Patriarch Photrius (858-867) sent them a bishop, later they probably adopted Christianity. Another tradition of the same period tells about the baptism of Prince Askold (882) under the Patriarch of Constantinople Photius, but today it is not possible to say whether it is true. At the same time, in the lands adjacent to Rus’, Sts Cyril and Methodius, Equal to the Apostles, started their missionary activities. In about 860, on the road to Khazaria St. Cyril visited Crimea, where he found the relics of the martyred Pope St. Clement I (88-99), who was exiled to these then-outlying districts of the Roman Empire in the late 1st century A.D.
In 864, at the invitation of Prince Rastislav of Great Moravia, Cyril and Methodius began in that state a Christian Mission extending into the territory of present day Slovakia, Czechia, Hungary, Poland and Ukraine.
Subsequently, the holy brothers were blessed for a mission by both Popes Adrian II and John VII (872-882). Historians, however, are still debating the detailed scope of the jurisdiction of the Slavic hierarchy of Great Moravia. In fact, its influence on the Christianization of the contemporary Transcarpathian and Galician territories of Western Ukraine is quite unlikely. There is a hypothesis that the beginnings of the ancient Eparchy of Peremyshl may date back to the time of St. Methodius’ archbishopric, but there is not enough conclusive evidence. After their banishment from Moravia, the Cyril and Methodius’ disciples settled in the neighboring Kingdom of Bulgaria, whose borders included part of the present-day southwestern Ukraine. Thus, at some point, the Cyril and Methodius tradition actually did have influence on Rus’ due to these Slavic enlighteners’ disciples and their writings coming from Bulgaria. An account of the glorious activity of these, Equal to the Apostles, can be found in the Tale of Bygone Years also knowns as the Primary Chronicle.
The Chronicle tells us of the existence of the Christian church of St. Elias in Kyiv at the time of Prine Ihor in 944. This indicates, that though not being an officially Christian state, Rus’ was not entirely pagan at that time. Christian preaching penetrated these lands through trade and international contacts. An important milestone of the spread of Christianity in Ruthenian lands was the baptism of Princess regent Olha in 954/55.