Following the lead of Philo Judaeus, Christian theologians strove to demonstrate that their religion was more than merely an appealing myth - that it could hold its own in the highest intellectual circles. Plato and the Bible agreed, so they argued, on the existence of a single God and the importance of living an ethical life. But as Christians explored their faith more analytically, they began to differ among themselves on such difficult issues as the nature of Christ (how could he be both God and man?) and the Trinity (how can three be one?). Some opinions were so inconsistent with the prevailing view that they were condemned as "heresies". As questions were raised and orthodox solutions agreed on, Christian doctrine became increasingly specific and elaborate.
The early heresies sought to simplify the nature of Christ and the Trinity. One group, the Gnostics, insisted that Christ was not truly human but only a divine phantom - that God could not have degraded himself by assuming a flesh-and-blood body. Others maintained that Christ was not fully divine, not an equal member of the Trinity. This last position was taken up in the fourth century by a group of Christians known as Arians (after their leader, Arius), who spread their view throughout the Empire and beyond.
The orthodox position lay midway between Gnosticism and Arianism: Christ was fully human and fully divine. He was a coequal member of the Holy Trinity who had always existed and always would, but who had assumed human form and flesh at a particular moment in time and had walked the earth, taught, suffered and died as the man Jesus.
