St Augustine (Aurelius Augustinus (354–430 ce), was born at Thagaste (mod. Souk Ahras, Algeria), son of Patricius, a modest town councillor of pagan beliefs, and a dominant Catholic mother, Monica. Educated at Thagaste, *Madauros, and Carthage, he taught rhetoric at Thagaste, Carthage, and Rome and (384–6) as public orator at Milan, then the capital of the emperor Valentinian II. Patronized at Rome by *Symmachus (2), the pagan orator, he hoped, by an advantageous marriage (to which he sacrificed his concubine, the mother of a son, Adeodatus—d. c.390) to join the ‘aristocracy of letters’ typical of his age (see ausonius). At 19, however, he had read the Hortensius of *Cicero. This early ‘conversion to philosophy’ was the prototype of successive conversions: to *Manichaeism, a Gnostic sect promising Wisdom, and, in 386, to a Christianized *Neoplatonism patronized by *Ambrose, bishop of Milan. Catholicism, for Augustine, was the ‘Divine Philosophy’, a Wisdom guaranteed by authority but explored by reason: ‘Seek and ye shall find’, the only scriptural citation in his first work, characterizes his life as a thinker.
Author of a comprehensive philosophical polemic against *Christianity, The True Doctrine, written probably between 175 and 181 (Origen, C. Cels. 8. 69, 71). The work is primarily known through *Origen (1)'s Contra Celsum, which directly quotes selected passages. Celsus wrote from the perspective of a Middle Platonic philosopher, though in one section of his work he also appears to have adopted the criticism levelled against Christianity by a Jew (Origen, C. Cels. 1. 28). The True Doctrine is important evidence for knowledge of Christian doctrine among Gentiles, as well as for the difficulty outsiders had in determining the difference between ‘orthodox’ Christians and *Gnostic fringe groups (Origen, C. Cels. 5. 61 ff.). The importance of Celsus’ book is suggested by the fact that Origen's massive refutation was written in the 240s.Efforts to identify this Celsus with the Celsus who is the addressee of Lucian's Alexander are not convincing: the author of The True Doctrine was a Platonist, while the recipient of the Alexander was evidently an Epicurean.
The background of early Christian demonology was in both Hebrew and Greek culture. Jews associated the Greek word daimōn with the false gods of the surrounding nations. This was in many ways an intuitive application of the Greek term. It carried the sense of ambivalent divine or semi-divine power, which significant philosophical traditions understood to mediate between humans and gods. The New Testament carries this theme, though its focus is more on Christ’s exorcisms of demons, and his gift of that power to his disciples, with the early church tying the two together in the theological literature, as well as baptismal exorcisms and renunciations of the devil and idolatry.Demons were widely thought to have aerial bodies, which allowed them to perform various marvels, like foretelling the future. They were ultimately taken to be fallen angels with Satan as their leader, though this was not a given early in the tradition. While the Christian understanding was that Christ had defeated them on the cross, this was not taken to preclude the ongoing influence of demons in human affairs prior to the final judgement. Indeed, they constituted a significant moral problem for the Christian life, which absolutely opposed them. For Christians, Christ and the demons were the two sides of the fundamental dilemma of every human soul. The problem of demons manifested differently depending on the context, whether in its encounter with false religion, from idolatry to the persecutions the gods inspired; or in the innumerable tempting thoughts encountered in the pursuit of ascetic discipline.
John Philoponus (c. 490ce to 570s), a Christian Neoplatonist (see neoplatonism) in *Alexandria (1), influenced subsequent science down to Galileo by replacing many of *Aristotle's theories with an account supporting Christian ideas. But because his own Christian theology was unorthodox, he was anathematized in 680, and his scientific influence came to the West belatedly through the Arabs. Seven early commentaries on Aristotle survive, four described as taken from the seminars of his Alexandrian teacher Ammonius, although he added his own ideas. In 529, the Christian emperor *Justinian closed the other great Neoplatonist school at Athens, and Philoponus published an attack on the Athenian Neoplatonist *Proclus, who had been Ammonius' own teacher. This attack (Against Proclus On the Eternity of the World) was followed by Against Aristotle on the Eternity of the World. In these two works Philoponus used arguments about infinity to prove the Christian view that the universe must have had a beginning. Otherwise it would have finished going right through a more than finite number of years, which his opponents regarded as impossible. Further, Aristotle ought to have analyzed corporeal matter as a kind of three-dimensional extension, not as an unextended substratum. Moreover, Aristotle's dynamics was wrong. Motion in a vacuum is theoretically possible. Again, projectiles are moved by an internal impetus impressed from outside, not by Aristotle's external forces.