In the tradition, monotheistic notions of God and the soul were read into Plato and Aristotle. Just using the word “God” or “soul” in later times immediately invoked strong connotations from a monotheistic background that were very different from Plato and Aristotle’s context.
Plato’s dialogues do famously talk about immortality of the soul, but the notion there has neither the very strong unity nor the strong personal identity attributed to the soul in the monotheistic religions. In the Republic, the unity of the soul is likened to that of a city, and elsewhere there is talk of reincarnation. (See also Plato on the Soul.)
Aristotle’s notion of soul is biological (way of life of a living body), not metaphysical. He specifically says the soul is not like the pilot of a ship, and that memory (which Locke made the basis of personal identity) depends on the body. (See also Parts of the Soul; Aristotelian Subjectivity.)
Plato and Aristotle speak of theos or theoi (the divine or god, or gods) as good, as intellect, and as in a state of perfect happiness. Most of what Plato says is in his poetic mode. Aristotle is extremely circumspect.
There is no creation from nothing in Plato, and no creation at all in Aristotle. There is some kind of providence, but it is very general, for Aristotle clearly applying only to the order of the cosmos and not to particular events. Plato’s dialogues speak of divine inspiration, but also compare it to a kind of madness. Aristotle says philosophy begins in wonder, and that the delight we take in the senses shows that man by nature desires to know. Both emphasize the eternity of the divine and the divinity of the order of nature. There is no concept of any special intervention in the order of nature.
I believe Plato and Aristotle would likely have endorsed Leibniz’s critique of the consequences of attributing an unconstrained, counterfactually omnipotent will to God. Leibniz said this was a theological disaster that made of God an arbitrary tyrant. (See also Euthyphro; Tyranny.)
Theological and anthropological voluntarism have a long history. Philo of Alexandria, early Augustine, al-Ghazali, the Franciscan theologians, and Descartes all contributed. Spinoza and Leibniz spoke well on this subject. (See also Psyche, Subjectivity; Theology.)