Neoplatonism was a major influence on Christian theology throughout Late Antiquity and the Middle Ages in the West. This was due to St. Augustine of Hippo, who was influenced by the early Neoplatonists Plotinus and Porphyry, as well as the works of the Christian writer Dionysius the Pseudo-Areopagite, who was influenced by later Neoplatonists, such as Proclus and Damascius.
Certain central tenets of Neoplatonism served as a philosophical interim for the Christian theologian Augustine of Hippo on his journey from dualistic Manichaeism to Christianity. As a Manichee, Augustine had held that evil has substantial being and that God is made of matter; when he became a Neoplatonist, he changed his views on these things. As a Neoplatonist, and later a Christian, Augustine believed that evil is a privation of good and that God is not material. Perhaps more importantly, the emphasis on mystical contemplation as a means to directly encounter God or the One, found in the writings of Plotinus and Porphyry, deeply affected Augustine. He reports at least two mystical experiences in his Confessions which clearly follow the Neoplatonic model. According to his own account of his important discovery of 'the books of the Platonists' in Confessions Book 7, Augustine owes his conception of both God and the human soul as incorporeal substance to Neoplatonism.
When writing his treatise 'On True Religion' several years after his 387 baptism, Augustine's Christianity was still tempered by Neoplatonism, but he eventually decided to abandon Neoplatonism altogether in favor of a Christianity based on his own reading of Scripture.