The Orthodox Church leaders of Moscow and Constantinople, from which Prince Vladimir the Great took Christianity, joining Eastern Orthodoxy, are expected to visit the Ukrainian capital this week.
The Christianization of Kiev dates from late 988, when Prince Vladimir the Great was baptized at Chersonesos, in the Crimea. He then baptized his family and people in Kiev and destroyed wooden statues of Slavic pagan gods.
The baptism of Kiev was followed by similar ceremonies in other areas of ancient Rus, where people were often forced to accept the new religion "by fire and the sword."
Speaking ahead of the anniversary, Ukrainian President Viktor Yushchenko said he hoped the event would encourage unity among the country's Orthodox communities.
"The head of state has expressed hope that a process of unification [among Orthodox churches] will be encouraged by the celebrations of the 1,020th anniversary of the Baptism of Kievan Rus," the presidential press service said on Thursday.
The Ukrainian Orthodox Church, subordinate to the Moscow Patriarchy, is currently the only Ukrainian church with a canonical standing in Eastern Orthodoxy and has full communion with the other Eastern churches. According to official data, it is the largest religious body in the country, predominant in the east and south.
Other Orthodox churches in the country include the Ukrainian Orthodox Church - Kiev Patriarchy, which broke away from the Russian Orthodox Church in 1989, and the Ukrainian Autocephalous Orthodox Church. The latter obtained autonomy from Moscow after the breakup of the Russian empire and the Bolshevik revolution.
Kiev Patriarchy officials have recently stepped up contacts with the Church of Constantinople, also known as the Ecumenical Patriarchate, seeking "to return Ukraine to the Mother Church." The drive has been proactively backed by President Yushchenko and the country's other top officials against the backdrop of ongoing tensions in relations with Russia.
Russian church officials said on Thursday that the Moscow and Constantinople Patriarchates had agreed ahead of the holiday "to rule out" the participation of leaders of the "schismatic churches" in services and other events in Kiev to celebrate the anniversary.
Patriarch Alexy II of Russia and Patriarch Bartholomew I of Constantinople will meet in Kiev on Sunday.
President Yushchenko and Bartholomew I will hold a reception in the sumptuous 11th century St. Sophia Cathedral on Saturday. The patriarch, along with Orthodox hierarchs from other countries, will hold a service near a statue to Holy Prince Vladimir the following day.