(484–519), in Christian history, split between the patriarchate of Constantinople and the Roman See, caused by an edict by Byzantine patriarch Acacius that was deemed inadmissible by Pope Felix III. (Felix III, Saint)

With the support of the Byzantine emperor Zeno, Acacius in 482 drew up an edict, the Henotikon (Greek: “Edict of Union”), by which he attempted to secure unity between orthodox Christians and monophysites. The Henotikon's theological formula incorporated the decisions of the general Councils of Nicaea (325) and Constantinople (381) and recognized Christ's divinity, but it omitted any reference to the orthodox distinction of Christ's human and divine essences, as enunciated by the Council of Chalcedon (451), and in so doing made important concessions to the monophysites. The Henotikon was widely accepted in the East but proved unacceptable to Rome and the Western church. Consequently, Acacius was deposed (484) by Pope Felix III in an excommunication that was reaffirmed and broadened in 485 to embrace all of Acacius' accomplices, including a substantial part of the Byzantine hierarchy. The condemnation by Pope Felix precipitated the Acacian Schism, which was not resolved until 519.