Classical theism’s ancestry includes Plato, Aristotle, Middle Platonism and Neoplatonism. It entered Judaism through Philo of Alexandria (§4), reaching its apogee there in Maimonides (§3). It entered Christianity as early as Irenaeus and Clement of Alexandria and became Christian orthodoxy as the Roman Empire wound down. Though more and more challenged after 1300, it remains orthodox. Classical theism filtered into Islam as early as al-Kindi (§§1–2). Al-Ghazali attacked it as the view of Islamic Aristotelians, and it suffered in Islamic orthodoxy’s successful reaction against Aristotle.