Eastern Orthodox
Eastern Orthodoxy is the communion centered on Constantinople after the mutual excommunications of 1054. Its national churches are self-governing organizations of one communion, not divisions. The true forks on this tree are the Old Believers of 1666, the Old Calendarists of 1924, and the contested Ukrainian autocephaly of 2018.
On the tree
Solid lines are separations and unions; dashed lines are renewals that began inside a body; dotted gray lines are national organizations of one communion; a diamond marks a fork event where neither side is drawn as the one that left. Every line runs back to the post-apostolic church; no body descends from the assembly of Acts 2.
Bodies in this family
The largest autocephalous Orthodox church, from the Baptism of Rus' (988) through the Moscow patriarchate (1589), the synodal era, Soviet persecution and revival — mother trunk of the Old Believer, ROCOR, OCA, and Ukrainian entries in this file.
The Greek-speaking communion centered on Constantinople after the mutual excommunications of 1054 — censures personal in scope, lifted from memory in 1965, with the schism itself unhealed. Autocephaly structure is annotation, not division.
- Old Believers1666–1667
Russians who held the pre-Nikonian rite — the two-finger cross, the old service books — against reforms aligning Russian practice with the Greeks; anathematized in 1666–67, they divided into priested (popovtsy) and priestless (bespopovtsy) concords under centuries of persecution. Reconciliation annotations: the toleration edict of 1905, and the ROC's rescinding of the anathemas in 1971.
- Church of Greece1850
Greek independence made an Ottoman-seated patriarch's jurisdiction untenable; the state declared autocephaly in 1833 and Constantinople regularized it by the tomos of 1850 — the pattern-case for every Balkan autocephaly after it.
- Russian Orthodox Church Outside Russia1920 · reunited
The Russian exile church, refusing communion with a patriarchate it judged captive to the Soviet state; eight decades of parallel existence ended by the 2007 Act of Canonical Communion — the fork-and-rejoin showcase of the whole tree.
- Old Calendarists1924–1935
Traditionalists who broke communion over the 1924 calendar reform — holding that only an ecumenical council could alter what one had fixed. Precision matters: keeping the Julian calendar is not Old Calendarism (the ROC keeps it in full communion); the fork is severed communion, and the movement has since fragmented into many rival synods.
The American church of the Russian mission line, granted autocephaly by Moscow in 1970 with a vision of a united territorial church for North America; the grant's disputed recognition is itself a live datum about how autocephaly works.
Ukraine's autocephalous church, formed by the 2018 unification council under Constantinople's auspices amid the Russo-Ukrainian conflict; recognized by some autocephalous churches, rejected by Moscow, with the UOC-MP continuing in parallel — live history, stated from both sides without adjudication.
Claimed lineage
What this tradition says about its own origin · apostolic see
The Orthodox Church is the spiritual successor of the apostolic community through the unbroken succession of its bishops, and in its official self-understanding is singularly the one true Church — schisms occur FROM the Church, never within it.
Its own sources: Matthew 16:18; 28:20 (as cited in Orthodox teaching); official synodical statements (e.g., rejections of the branch theory).
The documented record: Mirror-symmetric with Rome's claim across 1054; the tree's mutual_excommunication grammar deliberately declines to adjudicate what these two cards each assert.
Research compiled July 2026. Page data built 2026-10-10.