Eastern Orthodoxy by country
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. The most common estimates of the number of Eastern Orthodox Christians worldwide is approximately 200–260 million. The numerous Protestant groups in the world, if taken all together, outnumber the Eastern Orthodox, but they differ theologically and do not form a single communion.
Orthodox Judaism
In the State of Israel, where the total Jewish population is about 6.5 million, 22% of all Jewish respondents to a 2016 PEW survey declared themselves as observant Orthodox (9% "Haredim", or "Ultra-Orthodox", 13% "Datiim", "religious"). 29% described themselves as "traditional", a label largely implying little observance, but identification with Orthodoxy. The second largest Orthodox concentration is in the United States, where a 2013 PEW survey found that 10% of respondents identify as such, in a total Jewish population of at least 5.5 million. 3% were Modern Orthodox, 6% were Ultra-Orthodox, and 1% were "other" (Sephardic, liberal Orthodox, etc.) In Britain, of 79,597 households with at least one Jewish member that held synagogue membership in 2016, 66% affiliated with Orthodox synagogues: 53% in "centrist Orthodox", where congregants are often lax in observance, and 13% in "strictly Orthodox" (further 3% were Sephardi, which technically eschews the title "Orthodox").