Both neo-Platonic and Christian theology tried to prove that their respective religious convictions were the only true source of salvation. Both originated in the Alexandrian School. Christian theology was preceded by the fantastic system of the Gnostics, as Plotinus was preceded by the Pythagoreans and Philo. In their development the differences between the two appear. Christianity was supported by a church organization which had an internal vitality and a regulative power; neo-Platonism was supported and regulated by individuals, without organization, who had assimilated every faith. Christian theology was founded on a faith that had already expanded, while neo-Platonism was at the beginning an erudite religion that tried to develop an extended faith and, incidentally, later to assimilate other cults. Outwardly neo-Platonism, as the final stand of the pagan world to save itself from destruction, was unsuccessful in that it failed to perpetuate itself as an organization. Really it achieved a marked success. Not only did it live a long life of two hundred and fifty years, but it also lived in the development of its antagonist, Christianity. For neo-Platonism, by the irony of fate, was one of the important factors that entered into the building up and strengthening of Christianity. In its lingering death-struggle Hellenism was creating the conceptions that the Christian, Augustine, later employed in shaping Christian theology for the Middle Ages. =The Periods of Neo-Platonism.= (1) The Alexandrian School――about 240. Neo-Platonism presented as a Scientific Theory. The leader was Plotinus (204–269). (2) The Syrian School――about 310. The Attempt to Systematize all Polytheisms. The leader was Jamblichus (d. about 330). (3) The Athenian School――about 450. The Recapitulation of Greek Philosophy. The leader was Proclus (410–485).