Origen (c. 185 - 254 A.D.) is generally considered the greatest theologian and biblical scholar of the early, Eastern church.  He was probably born in Egypt, perhaps in Alexandria, to a Christian family.  His father Leonides had given him an excellent literary education.  However, his father died in the persecution of 202 and Origen narrowly escaped the same fate.  At 18 years old, where he had been a student, Origen was appointed to succeed Clement of Alexandria as head of the catechetical school of Alexandria.

Between 203 and 231, Origen attracted large numbers of students through his manner of life and through his teaching.  During this time, Origen traveled widely and while in Palestine (c. 215), he was invited to preach by local bishops, even though he was not ordained.  Demetrius, the bishop of Alexandria, regarded this activity as a breach of discipline and ordered him to return to Alexandria.  The period following, from 218 to 230, was one of Origen's most productive as a writer.

In 230, he returned to Palestine, where he was ordained as a priest by the bishops of Jerusalem and Caesarea.  Demetrius then excommunicated Origen, deprived him of his priesthood and sent him into exile. Origen decided to settle at Caesarea and founded a school of literature, philosophy and theology.  During the persecutions of the Christians in 250, under Emperor Decius, Origen was imprisoned and tortured.  Released in 251, but weakened by injuries, he died in about 254 (probably in Tyre).

Origen's literary productivity was enormous. His accomplishments as an exegete and student of the text of the Old Testament were outstanding. His works include letters, treatises in dogmatic and practical theology, apologetics, exegeses, and textual criticism. "Contra Celsum" (also called "Contra Celsus" and "Against Celsus") is a closely reasoned, long, apologetic work refuting arguments advanced by the philosopher Celsus.  Celsus was an influential, 2nd-century Platonist of Alexandria and perhaps the first serious critic of Christianity.

Incidentally, Origen held some viewpoints that 21st century Christians would consider unbiblical.  For example, he thought that the soul pre-existed and he even believed that Satan would be saved one day!  Nonetheless, his literature was interesting and well-preserved for such ancient documents.  He also defended the main doctrines of Christianity and helped advance a blended approach of philosophy and theology.