I need to add something here.
The Catholic Encyclopedia article on neo-platonism begins with this paragraph:
"A system of idealistic, spiritualistic philosophy, tending towards mysticism, which flourished in the pagan world of Greece and Rome during the first centuries of the Christian era. It is of interest and importance, not merely because it is the last attempt of Greek thought to rehabilitate itself and restore its exhausted vitality by recourse to Oriental religious ideas, but also because it definitely entered the service of pagan polytheism and was used as a weapon against Christianity."