Eusebius

Eusebius of Caesarea (; Greek: Εὐσέβιος τῆς Καισαρείας, Eusébios tés Kaisareías; AD 260/265 – 339/340), also known as Eusebius Pamphili (from the Greek: Εὐσέβιος τοῦ Παμϕίλου), was a historian of Christianity, exegete, and Christian polemicist. He became the bishop of Caesarea Maritima about 314 AD. Together with Pamphilus, he was a scholar of the Biblical canon and is regarded as an extremely learned Christian of his time. He wrote Demonstrations of the Gospel, Preparations for the Gospel, and On Discrepancies between the Gospels, studies of the Biblical text. As "Father of Church History" (not to be confused with the title of Church Father), he produced the Ecclesiastical History, On the Life of Pamphilus, the Chronicle and On the Martyrs. He also produced a biographical work on the first Christian Emperor, Constantine the Great, who ruled between 306 and 337 AD. During the Council of Antioch, which was convened in 325 and held shortly before the First Ecumenical Council in the Bythnian city of Nicaea, he was excommunicated for subscribing to the heresy of Arius.The debate raged over whether Christ is of the "same substance" (homoousion), or "similar substance" (homoiousian) to the Father. This was no exercise in semantics, for if Christ is of the 'same substance', or 'essence' as the Father, then this testifies to His divinity. On the other hand, if Christ is of 'similar substance' to the Father – as Arius believed, then this testifies that Christ had a beginning in time, is therefore subordinate to the Father and is little more than a created being. While the Greek fathers of the church applied the Aristotelian term ousia to the divine essence of God, it translated into Latin as essentia, or substantia (substance). The Greek term homoousios was consequently translated into Latin as coessentialis or consubstantialis, which in English translates as coessential and consubstantial. Thus the test for heresy at Nicaea was based upon what eventually became the orthodox