Neoplatonism was an early influence on Christian thinkers. The Christian apologists Clement of Alexandria and Origen had vied with the incipient Neoplatonic tradition for control of the Platonic heritage. The philosophy was firmly joined with Christianity by St. Augustine, who was a Neoplatonist before his conversion. It was through Neoplatonism that Augustine conceived of spirit as being immaterial and viewed evil as an unreal substance (in contradistinction to Manichaean doctrine). The writings of Pseudo-Dionysius (see Dionysius the Areopagite) and Boethius display Neoplatonic influences.
In the Middle Ages, elements of Plotinus' thought can be found in St. Thomas Aquinas and John Scotus Erigena, particularly in the identification of the One with God and the Divine Mind with the angels. The system influenced medieval Jewish and Arab philosophy, and G. W. F. Hegel's metaphysics had Neoplatonic ingredients. Neoplatonic metaphysics and aesthetics also influenced the German Romantics (see romanticism), the 17th-century English metaphysical poets, William Blake, and the Cambridge Platonists. Many mystical movements in the West, including those of Meister Eckhardt and Jacob Boehme, owe something to the Neoplatonists.