Eastern Orthodoxy by country
The number of members of the Eastern Orthodox Church in each country has been subject to a lot of debate. 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 these 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. A case of this is the United States, which has large numbers of immigrants from Eastern Orthodox countries. The Eastern Orthodox jurisdictions often reported large numbers of members, which together would total 2-3 million across the country. However, a 2010 study by Alexei Krindatch sought data from each parish, with the specific criteria of annual participation. This study produced the "Atlas of American Orthodox Christian Churches", and discovered that there were only about 817,000 Eastern Orthodox Christians actively practicing their faith (that is to say, 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.
Christianity in the Middle East
The percentage of Christians in Turkey fell from 19 percent in 1914 or 3 million (thought to be an undercount by one-third omitting 600000 Armenians, 500000 Greeks and 400000 Assyrians) to 2.5 percent in 1927 in a population of 14 million, due to events which had a significant impact on the country's demographic structure, such as the Armenian Genocide, the population exchange between Greece and Turkey, and the emigration of Christians (such as Levantines, Greeks, Armenians etc.) to foreign countries (mostly in Europe and the Americas) that actually began in the late 19th century and gained pace in the first quarter of the 20th century, especially during World War I and after the Turkish War of Independence. Today there are more than 160,000 people of different Christian denominations, representing less than 0.2 percent of Turkey's population, including an estimated 80,000 Oriental Orthodox, 35,000 Roman Catholics, 18,000 Antiochian Greeks, 5,000 Greek Orthodox and smaller numbers of Protestants (Mostly ethnic Turkish). Currently there are 236 churches open for worship in Turkey. The Eastern Orthodox Church has been headquartered in Istanbul since the 4th century.