The definitions came out of a fifth-century fight. Nestorius, in stressing the distinctness of the two natures, resisted calling Mary Theotokos, "God-bearer"; Cyril of Alexandria, insisting the child born was one and the same as the divine Son, prevailed at the Council of Ephesus in 431. Twenty years later the Council of Chalcedon (451) issued the classic formula: one person "in two natures, without confusion, without change, without division, without separation", four adverbs, each closing off a specific error.
That definition became a permanent fault line, and the atlas records the surviving positions rather than ranking them. The Chalcedonian confession is held by the Catholic, Eastern Orthodox, Anglican and Reformation churches. The Miaphysite churches, Coptic, Syriac, Armenian, Ethiopian and others, follow Cyril's formula of "one incarnate nature of the Word" and rejected Chalcedon's language as tending toward division; they are not the same as the condemned Eutychians, a point recent dialogues have largely conceded. The Church of the East kept the Antiochene emphasis later labelled Nestorian. The Arian reading, which denied the Son's full divinity, was condemned at Nicaea. Late-twentieth-century Christological agreements have concluded that much of the Chalcedonian-Miaphysite split was verbal, though the churches remain distinct.