Eastern Orthodox Church

=== Traditionalist groups ===

==== True Orthodox ====

{{Main|Eastern Orthodox Church organization#True Orthodox}}

[[True Orthodoxy]] has been separated from the mainstream communion over issues of ecumenism and calendar reform since the 1920s.<ref name=politika2>{{cite web|url=http://www.politika.rs/rubrike/Drustvo/Ko-su-ziloti-pravoslavni-fundamentalisti.lt.html|title=Ko su ziloti, pravoslavni fundamentalisti|author=Beoković, Jelena|date=1 May 2010|publisher=[[Politika]]|trans-title=Who are Zealots, Orthodox Fundamentalists|access-date=5 August 2014}}</ref> The movement rejects the Ecumenical Patriarchate of Constantinople, the Moscow Patriarchate, and all churches which are in communion with them, accusing them of heresy and placing themselves under bishops who do the same thing. They adhere to the use of the [[Julian calendar]], claiming that the [[Revised Julian calendar|calendar reform in the 1920s]] is in contradiction with the ecumenical councils. There is no official communion of True Orthodox; and they often are local groups and are limited to a specific bishop or locality.

==== Old calendarists ====

{{Main|Old Calendarists}}

==== Old Believers ====

{{Main|Old Believers#Old Believer churches}}
[[File:Crucession_Davidovo-Elizarovo_Guslitci_Moscow_reg_8504.jpg|thumb|Traditional [[Easter|Paschal]] procession by [[Russian Orthodox Old-Rite Church]]]]

[[Old Believers]] are groups which do not accept the liturgical reforms which were carried out within the Russian Orthodox Church by [[Patriarch Nikon of Moscow]] in the 17th century. Although all of the groups of Old Believers emerged as a result of opposition to the Nikonian reforms, they do not constitute a single monolithic body. Despite their emphasis on invariable adherence to the pre-Nikonian traditions, the Old Believers feature a great diversity of groups which profess different interpretations of church tradition and they are often not in communion with each other (some groups even practise re-baptism before admitting a member of another group into their midst).