The label Nestorian Church, long used in Western scholarship and popular reference to describe this body, is one the church's own Holy Synod has formally asked not be used, since the church's actual Christology does not match the position historically attributed to the Constantinople patriarch Nestorius whose condemnation at Ephesus in 431 precipitated the original split. Modern historical theology increasingly reads the fifth century controversy as driven substantially by imprecise Greek and Syriac theological vocabulary and by political rivalry between rival sees as much as by a clear, settled doctrinal heresy on either side, a reassessment that has led some churches, including the Roman Catholic Church, toward formal joint declarations narrowing the theological distance once assumed to separate them entirely.
The church is headed today by a Catholicos-Patriarch, a title tracing back to its ancient status as the senior bishopric of the Christian communities under Persian rather than Roman rule, and it maintains full communion and cooperation with the smaller Ancient Church of the East, a twentieth century jurisdictional split from the same tradition, while remaining doctrinally and liturgically distinct from the Chaldean Catholic Church, the body of former Church of the East Christians who entered communion with Rome beginning in the sixteenth century.
This atlas records the Assyrian Church of the East on its own terms, honoring the Synod's request regarding terminology, and treats its survival through genocide and mass displacement into the twenty first century as a defining fact of its modern identity rather than a peripheral historical footnote to an otherwise purely ancient story.