Christianity rejected all forms of a dual origin of the world which erected matter, or evil, or any other principle into a second eternal being coexistent with God, and it taught the monistic origin of the universe from one, infinite, self-existing spiritual Being who freely created all things. The unfamiliar conception of free creation, however, met with considerable opposition in the schools of philosophy and was abandoned by several of the earlier heresies. The neo-Platonists sought to lessen the difficulty by emanastic forms of pantheism, and also by inserting intermediate beings between God and the world. But the former method implied a materialistic conception of God, while the latter only postponed the difficulty. From the thirteenth century, through the influence of [[Albertus Magnus]] and still more of St. Thomas [[Aquinas]], the philosophy of Aristotle, though subjected to some important modifications, became the accredited philosophy of the Church. The dualistic hypothesis of an eternal world existing side by side with God was of course rejected. But the conception of spiritual beings as opposed to matter received fuller definition and development. The distinction between the human soul and the body which it animates was made clearer and their separability emphasized; but the ultra-dualism of Plato was avoided by insisting on the intimate union of soul and body to constitute one substantial being under the conception of form and matter. [Source](https://www.newadvent.org/cathen/05169a.htm)