Based on the numbers of adherents, the Eastern Orthodox Church (also known as Eastern Orthodoxy) is the second largest Christian communion in the world, after the Roman Catholic Church, with the most common estimates of baptised members being approximately 220 million.[1][2][3] The numerous Protestant groups in the world, if taken all together, substantially outnumber the Eastern Orthodox,[4] but they differ theologically and do not form a single communion.[5]
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In 2025, Russia was home to most of the world’s Eastern Orthodox Christians, with 101.5 million of them living within Russia borders (72%); at the same time, Ukraine had 27.8 million people following the religion (65.4%), followed by Romania (16.3 million or 81.1%), Greece (9.4 million or 90%) and Belarus (7.8 million or 83.3%).[6] It was the most popular religion in Moldova, with 93.3% of that country following Eastern Orthodoxy.
The percentage of Christians in Turkey, home to an historically large and influential Eastern Orthodox community, fell from 19% in 1914 to 2.5% in 1927,[19] due to genocide,[20] demographic upheavals caused by the population exchange between Greece and Turkey,[21] and the emigration of Christians to foreign countries (mostly in Europe and the Americas).[22] In 2021, there were 130,000 Orthodox Christians in Turkey (mainly adherents of the Armenian Apostolic Orthodox Church).[23] In 2022, there was a large increase in the number of Eastern Orthodox Christians in Turkey to over 150,000 people; this included approximately 100,000 people escaping the Russian invasion of Ukraine.[24]
In 2010, there were 40 million Eastern Orthodox Christians in Africa, although 39 million of them lived in Ethiopia or Eritrea; in 2021 and 2022, the Russian Orthodox Church opened more than 200 parishes throughout the continent, and had plans to build a cathedral in Johannesburg.[25]
There is no universal agreement on the number of members of the Eastern Orthodox Church in each country. Each study performed that seeks to discover the number of adherents in a country may use different criteria, and be submitted to different populations. As such, some numbers may be inflated, and therefore inaccurate. Examples of this are Greece and Russia, where estimates of adherence to Eastern Orthodoxy may reach 80–98%, but where surveys found lower percentages professing Eastern Orthodoxy or belief in God. The likely reason for this disparity is that many people in majority Eastern Orthodox countries will culturally identify with the Eastern Orthodox Church, especially if they were baptized as children, even if they are not currently practicing. This includes those who may be irreligious, yet culturally identify with the Eastern Orthodox Church, or for whom Eastern Orthodox Christianity is listed on official state records. Other cases of incongruent data also might be due to counting ethnic groups from Eastern Orthodox countries rather than actual adherents. For example, the Eastern Orthodox jurisdictions in the United States, which has large numbers of immigrants from Eastern Orthodox countries, have collectively reported a total of 2–3 million across the country.[citation needed]
However, a 2010 study by Alexei Krindatch sought data from each parish, with the specific criteria of annual participation, discovering that there were only about 817,000 Eastern Orthodox Christians actively practicing their faith (i.e., attending church services on a regular basis) in the United States. The study explained that such a difference was due to a variety of circumstances, for example the higher numbers having counted all people who self-identify as Eastern Orthodox on a census regardless of active participation, or all people belonging to ethnic groups originating in Eastern Orthodox countries. This study, while initially controversial, proved groundbreaking, and has since been officially approved for use by the Assembly of Canonical Orthodox Bishops of the United States of America.[citation needed]
The Eastern Orthodox Church is organized as a union of several autocephalous subdivisions, which are also called "Churches" (or, sometimes, "jurisdictions"). Some are associated with a specific country, while others are not. This table presents some known data regarding individual jurisdictions. "NA" means that data is not available.
^ abBrien, Joanne O.; Palmer, Martin (2007). The Atlas of Religion. Univ of California Press. p. 22. ISBN978-0-520-24917-2. There are over 220 million Orthodox Christians worldwide.
^Jay Diamond, Larry. Plattner, Marc F. and Costopoulos, Philip J. World Religions and Democracy. 2005, page 119.(also in PDF fileArchived 2008-04-13 at the Wayback Machine, p. 49), saying "Not only do Protestants presently constitute 13 percent of the world's population—about 800 million people - but since 1900 Protestantism has spread rapidly in Africa, Asia, and Latin America." "Archived copy"(PDF). Archived from the original(PDF) on March 25, 2009. Retrieved 2013-07-03.{{cite web}}: CS1 maint: archived copy as title (link)
^ ab"Русская православная церковь" (in Russian). Фонд Общественное Мнение, ФОМ (Public Opinion Foundation). 2 May 2024. Archived from the original on 16 May 2024. Retrieved 10 June 2024.
^İçduygu, Ahmet; Toktaş, Şule; Ali Soner, B. (1 February 2008). "The politics of population in a nation-building process: emigration of non-Muslims from Turkey". Ethnic and Racial Studies. 31 (2): 358–389. doi:10.1080/01419870701491937. hdl:11729/308. S2CID143541451.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Schaller, Dominik J; Zimmerer, Jürgen (2008). "Late Ottoman genocides: the dissolution of the Ottoman Empire and Young Turkish population and extermination policies - Introduction". Journal of Genocide Research. 10 (1): 7–14. doi:10.1080/14623520801950820. S2CID 71515470.
^Chapter The refugees question in Greece (1821-1930) in "Θέματα Νεοελληνικής Ιστορίας", ΟΕΔΒ ("Topics from Modern Greek History"). 8th edition. Nikolaos Andriotis. 2008.
^There is no official census of religion in Russia, and estimates are based on surveys only. In August 2012, ARENA determined that about 46.8% of Russians are Christians (including Orthodox, Catholic, Protestant, and non-denominational), which is slightly less than an absolute 50%+ majority. However, later that year the Levada CenterArchived 2012-12-31 at the Wayback Machine determined that 76% of Russians are Christians, and in June 2013 the Public Opinion Foundation website, How many Russians believe in God, go to church and pray their prayers? determined that 65% of Russians are Christians. These findings are in line with Pew's 2010 survey, which determined that 73.6% of Russians are Christians, with VTSIOM's 2010 survey (~77% Christian), and with Ipsos MORIArchived 2013-01-17 at the Wayback Machine's 2011 survey (69%).
^"Русская православная церковь" (in Russian). Фонд Общественное Мнение, ФОМ (Public Opinion Foundation). 2 May 2024. Archived from the original on 3 May 2024. Retrieved 10 June 2024.
^The ROC severed full communion with the Ecumenical Patriarchate in 2018, and later severed full communion with the primates of the Church of Greece, the Patriarchate of Alexandria, and the Church of Cyprus in 2020.
^ abcdefghiAutocephaly or autonomy is not universally recognized.
^UOC-MP was moved to formally cut ties with the ROC as of May 27th 2022.
^Semi-autonomous part of the Russian Orthodox Church whose autonomy is not universally recognized.