A Palestinian born Christian, E. received training in scholarship and theology from Pamphilus, a priest in Caesarea. P. expanded Origen's library, which he had left in that city, and was an avid student of his works-a quality he passed down to E. When P. was martyred in the Dioclecian persecution (from which E. fled to Egypt), E. took over his ecclesiastical responsibility and rose to bishop ca. 314. He held this position through the reign of Constantine, the first Chr. emperor, with whom E. collaborated and whom he celebrated. He attempted to negotiate a via media between Arian and Nicene theologies, but was ultimately unsuccessful because his neo-Origenist ideas could not consistently hold. E. reluctantly signed the Nicene creed in 325 at the instigation of Constantine. In his ecclesiastical career, he continued this political/theological track by both deposing Eustathius of Antioch ca. 330 for Sabellianism and exiling Athanasius at the Synod of Tyre in 335.

Far and away, E.'s fame comes through his Historia ecclesiasticae in which he charted the history of the church from the close of the NT to the sole rule of Constantine in 324. In it, he tries to demonstrate that the purposes of God are being fulfilled in the Christianization of the Roman Empire, a fulfillment he sees as the apex of salvation history. His earliest apologetic work, the Eclogae propheticae, has been lost except for a few books which are a compilation of OT messianic prophecies with comments. The Praeparatio evangelica and the Demonstratio evangelica are his main work in two parts. The first proves the superiority of Chr. over paganism by arguing the surpassing antiquity and moral superiority of Judaism and Chr. by extension. The second part seeks to justify Chr.'s departure from Jewish religion, mostly by trying to demonstrate many OT passages have been fulfilled by Christ. His purpose in this two-fold work is primarily for Chr. instruction to reinforce its excellence and firm foundation in a time of instability before Constantine. One must also mention E.'s Onomasticon, a book filled with biblical place names which is still used today in considering biblical topography. E. had been to many of the places he discusses himself. Also, E. produced a number of exegetical works, focusing most on the prophets and the gospels, which can be viewed as consistent with his apologetic principles. In Christology, he wrote a work against Marcellus(Contra Marcellum) and his Sabellianism.

He saw himself first and foremost as a Chr. apologist, so that even his historical writings serve such a purpose. He used Origen heavily, but not uncritically. He inherited his textual critical bent, though he relies on the Greek text more than O. in OT exegesis. For his "imperial theology," the overriding purpose of the h.e . see "Reception."

The documentation of major church fathers and their writings contained in the h. e. has provided a wealth of information that otherwise may have been lost. E.'s theology of history-that God's action in salvation history can be identified with a specific political structure-has largely been discredited and repulsed in the modern age. While many considered him a heretic in his Christological views from the time of Jerome, in current scholarship, a more favorable view has begun to emerge based on a more nuanced approach to non-Nicene theology.