Neoplatonism:
Obviously there is more in the link. For me this school of thought has definitely influenced some of my spiritual beliefs in conjunction with buddhist and sufi philosophies.
Neoplatonism (also called Neo-Platonism) (Greek: Νεοπλατωνισμός, is the modern term for a school of mystical philosophy that took shape in the 3rd century CE, based on the teachings of Plato and earlier Platonists, with its earliest contributor believed to be Plotinus, and his teacher Ammonius Saccas. Neoplatonism focused on the spiritual and cosmological aspects of Platonic thought, synthesizing Platonism with Egyptian[1] and Jewish theology.[2] However, Neoplatonists would have considered themselves simply Platonists, and the modern distinction is due to the perception that their philosophy contained sufficiently unique interpretations of Plato to make it substantially different from what Plato wrote and believed.[3]
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Neoplatonism is generally a religious philosophy. Neoplatonism is a form of idealistic monism (also called theistic monism) and combines elements of Polytheism (see Monistic-polytheism).
Although the founder of Neoplatonism is supposed to have been Ammonius Saccas, the Enneads of his pupil Plotinus are the primary and classical document of Neoplatonism. As a form of mysticism, it contains theoretical and practical parts, the first dealing with the high origin of the human soul showing how it has departed from its first estate, and the second showing the way by which the soul may again return to the Eternal and Supreme. The system can be divided between the invisible world and the phenomenal world, the former containing the transcendent One from which emanates an eternal, perfect, essence (nous), which, in turn, produces the world-soul.
Obviously there is more in the link. For me this school of thought has definitely influenced some of my spiritual beliefs in conjunction with buddhist and sufi philosophies.