Classical theism is a form of theism in which God is characterized as the absolutely metaphysically ultimate being, in contrast to other conceptions such as pantheism, panentheism, polytheism, deism and process theism.
Classical theism is a form of monotheism. Whereas most monotheists agree that God is, at minimum, all-knowing, all-powerful, and completely good, classical theism asserts that God is both immanent (encompassing or manifested in the material world) and simultaneously transcendent (independent of the material universe); simple, and having such attributes as immutability, impassibility, and timelessness. A key concept in classical theism is that "created beings" (ie, material phenomena, whether sentient biological organisms or insentient matter) are dependent for their existence on the one supreme divine Being. Also, although God is wholly transcendent, he not only creates the material universe but also acts upon the material universe in imposing (or organizing) a Higher Order upon that material reality. This order was called by the ancient Greeks logos.
Classical theism is associated with the tradition of writers like Plato, Aristotle, Plotinus, Augustine, Anselm of Canterbury, Maimonides, Averroes and Thomas Aquinas. Since the advent of the scientific revolution in the seventeenth century the principle of divine immanence as a central doctrine of classical theism (as traditionally held by all three of the major Abrahamic religions) began to be replaced among progressive thinkers with the notion that although God had created the universe in the beginning he subsequently left the universe to run according to fixed laws of nature. A common metaphor for this idea in the seventeenth century was that of the clockwork universe. This theological doctrine was known as deism and gradually became the default view of many of the influential thinkers of the eighteenth century enlightenment.
Among modern day theologians and philosophers of religion classical theism has appeared in a number of variants. For example, there are, today, philosophers like Alvin Plantinga (who rejects divine simplicity), Richard Swinburne (who rejects divine timelessness) and William Lane Craig (who rejects both divine simplicity and timelessness),  who can be viewed as theistic personalists. Philosophers like David Bentley Hart and Edward Feser have defended traditional classical theism in recent times.
Classical theism was almost universal among Christian theologians prior to the twentieth century. However, some of its recent critics argue that it is taken from pre-Christian philosophers and incompatible with the occasions in the Bible that describe God as emotional or changing. In defence of classical theism's compatibility with the Bible, these passages can be read in an analogous or allegorical sense as containing poetic elements, just as many other passages have also long been read. For example, Exodus 31:18 describes "the finger of God", and Genesis 3:8 describes God as noisily walking in the garden of Eden. It is inconsistent that most Christian critics of classical theism would read these latter verses in an allegorical sense, but insist that instances which describe change or passion in God are extremely literal in meaning. Moreover, whereas critics of classical theism charge that it has infiltrated Christian theology from pre-Christian roots such as Neoplatonism, in fact the term "classical theism" belies crucial differences between a traditional Christian and Neoplatonic conception of God. For example, whereas Arius followed the neo-Platonist Plotinus in asserting that God could not become a physical man, Athanasius defended the doctrine of God's incarnation as the man Jesus, while nevertheless defending the immutability and impassibility of Jesus' divine nature. According to a traditional Christian understanding of the communicatio idiomatum, it can be rightly said that God suffered and died on the cross, but only by virtue of the hypostatic union of the impassible divine word with Jesus' passible human soul and body. Hence, while the church fathers made sure to correct the classical theism of pagan sources where it was incompatible with Christianity, it can be argued that many of the modern Christian critics of classical theism are in fact themselves influenced by an overly uncritical adoption of trends within process theology, which itself has non-Christian philosophical roots in the thought of Charles Hartshorne.