No central authority

Judaism

around 15 million adherents worldwide.

Estimate from Pew Research Center — The Future of World Religions.

What the sources state

The Union for Reform Judaism states that Reform Judaism's contribution has been to enable innovation while preserving tradition, and to affirm beliefs without rejecting those who doubt.

“The great contribution of Reform Judaism is that it has enabled the Jewish people to introduce innovation while preserving tradition, to embrace diversity while asserting commonality, to affirm beliefs without rejecting those who doubt, and to bring faith to sacred texts without sacrificing critical scholarship.”

Source: Union for Reform Judaism

Every quotation above was checked against its source on 3 September 2026.

Authority

Judaism has no central authority.

No body speaks for all Jews. The Hebrew calendar itself is fixed and arithmetic, so dates are computable, but movements differ on observance — notably on the second day of festivals in the diaspora.

Movements

Orthodox Judaism

Haredi Judaism

Hasidic Judaism

Conservative (Masorti) Judaism

Reform (Progressive) Judaism

Reconstructionist Judaism

Karaite Judaism

Observances in 2026

Observance	Dates	How certain
Purim Begins the evening of 2 March 2026	3 March 2026	Calculated
Passover Begins the evening of 1 April 2026	2–9 April 2026	Calculated
Shavuot Begins the evening of 21 May 2026	22–23 May 2026	Calculated
Tisha B'Av Begins the evening of 22 July 2026	23 July 2026	Calculated
Rosh Hashanah Begins the evening of 11 September 2026	12–13 September 2026	Calculated
Yom Kippur Begins the evening of 20 September 2026	21 September 2026	Calculated
Sukkot Begins the evening of 25 September 2026	26 September – 2 October 2026	Calculated
Shemini Atzeret Begins the evening of 2 October 2026	3 October 2026	Calculated
Simchat Torah Begins the evening of 3 October 2026	4 October 2026	Calculated
Hanukkah Begins the evening of 4 December 2026	5–12 December 2026	Calculated

Sources

Office of the Chief Rabbi (UK)
UK Orthodox Judaism
United Synagogue of Conservative Judaism
Conservative (Masorti) Judaism
Reform Judaism (UK)
UK Reform Judaism
Pew Research Center — The Future of World Religions
Demographic estimates
Union for Reform Judaism
Reform Judaism in the United States.
Masorti Judaism (UK)
Masorti (Conservative) Judaism in Britain.
Orthodox Union
American Orthodox Jewish congregations.
Karaite Jews of America
Karaite Judaism.
Sefaria
Jewish canonical text library. An archive, not a movement.

No expert review. Accuracy here rests on continuous machine verification of every quotation against its source. Spotted an error? Corrections are answered within five working days.