The concept of an “un-moved mover” has been discussed at least since the time of early Greek philosophers. Aristotle is most famously credited with establishing this idea, though he may not have been the very first to frame the concept this way. This line of reasoning and Aristotle’s argument in favor of it were later used in the context of Christian theology by Thomas Aquinas, who pointed to God as the Un-Moved Mover. This was part of Aquinas’ cosmological argument, one of his five ways. However, there are crucial differences between the way Aristotle viewed his un-moved mover and the way later theologians such as Aquinas used it as a reference to the God of the Bible.
Aristotle was a student of Plato, who taught that the ultimate reality was composed of ideal Forms, and that one primary “good” entity—the Demiurge—had created reality. Aristotle took a less personal and more abstract approach. He developed the idea of an un-moved mover from an earlier concept of un-moved movers (plural). Aristotle’s writings follow a chain of logic and observation to the idea that, in order for there to be “motion,” there had to be something to cause it: a “mover.” For Aristotle, however, this idea was applied individually to the various spheres of the heavens, which astronomers either numbered at 47 or 55. To Aristotle, these were not personal, relatable beings. They were pure intellectuality.
Later, however, Aristotle’s writings reflect either a change of mind or a growing conclusion, which changed his basic premise. In short, if there is more than one un-moved mover, there can be no unity in the uni-verse. This would then fall short as an ultimate explanation. So, it seems, Aristotle deduced there must, even behind the “movers” of the various celestial spheres, be a single, solitary, ultimate cause. Causality cannot end with multiple un-moved movers but must terminate with a single un-moved mover.
It should be noted that Aristotle’s concept of an un-moved mover is purely an abstraction, not a person. It is intellectual but not personal, in the sense of a being who interacts with others. Aristotle did not assume his first cause to be a person or even a deity. Instead, he viewed this ultimate cause as a “thought, thinking about itself.”
In a technical sense, this concept agrees well with the Bible’s depiction of God. God is the one who “began” creation, while Himself is uncreated (Genesis 1:1; John 1:1–3). He is Spirit (John 4:24), not essentially physical, so He could be somewhat described as “pure intellect.” In that sense, God is indeed the “Un-Moved Mover” or the First Cause. This is the gist of how Thomas Aquinas applied the idea of an un-moved mover to Christian theology.
Aristotle’s work is evidence of a principle found in the Bible: that God reveals enough of Himself in His creation to lead men to believe in Him. Psalm 19:1 indicates that “the heavens” show the work of God; Aristotle’s musings on astronomy were key to his conclusion that a final, ultimate cause must exist. Romans 1:19–20 says that “what can be known about God is plain” based on evidence everyone can see; from natural observations, Aristotle correctly deduced an un-caused, non-physical, “un-moved mover” responsible for the existence of the universe. What he did not realize, at least not fully, was that this conclusion points to an eternal, personal Creator (John 1:1–3).
In short, while Aristotle’s concept of an un-moved mover is compatible with the God of the Bible, Aristotle himself would not have identified a personal being such as God with his theory. To use an analogy, the God of the Bible is the completed puzzle, while Aristotle’s theory of an un-moved mover is just one piece. Simply speaking, Aristotle’s un-moved mover was not and is not the God of the Bible.