If God is light, and in Him is no darkness at all, how could He be said in Isaiah 45:7 to create darkness? How could an all-good being find material with which to create evil? For if He found it outside Himself, He is not the creator of all things.
To this I answer, not everything that is (even in this universe) needs specific creation to exist.
I believe shadows were not created specifically - they were a byproduct of the creation of light. So, did God create shadows? In a sense, yes - by creating light. But, in a sense, no. There was no specific creation of the shadow, since it technically does not exist (which, incidentally, is why it qualifies as a two-dimensional object in our universe). Darkness is merely the privation of light and is therefore nonexistent by the laws of our universe - it is simply a term we use as a tool to describe lack of light.
The same goes for heat and cold.
Dare I say the same goes for God and the devil? The devil is merely the shadow of God’s existence.
But then, doesn’t that mean the devil is eternal as God is?
No, I don’t believe so. The reason cold exists is not merely because heat exists, but because there is a law of cause and effect. The reason for cold is the effect of heat leaving. Theoretically, if the law of causation were revoked, one could have heat and no cold - light and no darkness. Of course, we would also be describing a universe entirely different than our own. But, since God was not ever bound by the laws of causality, there is no reason to suspect He had a shadow until He created a universe with cause and effect. That would signal the creation of the devil - not by special design, but by mere corollary of God’s existence coupled with the law of cause and effect.
But wouldn’t that mean the devil isn’t real, since darkness and cold are not technically real?
It depends on what you mean by real. God’s reality doesn’t fit within the laws of this universe - so He may be said to be scientifically unreal. Yet, by faith we perceive Him more real than the universe. The devil is unreal in the same way and real in a similar way. His effects are real, whereby we know he is real. Yet he is not perceptible with the five senses, though his spirit is everywhere. The devil is as real as hate is. Is hate real? It’s metaphysical, yet I suspect no one denies its reality in that sense.
But if the devil as the shadow of God came into existence at the inception of the universe with the creation of causality, doesn’t that mean he will cease to exist when this world and universe end?
No. No more than humans will. For we also were not eternally existent prior to conception, but we will live forever, whether in paradise or the second death where the worm never dies.
The atheist model of life is that humans are the supreme beings in the universe, but all organisms’ lifespans look like a geometrical vector (a line segment with direction).
Note that it has two points: a beginning and end, and is monodirectional.
The theistic model of life is that plants’ and animals’ lifespans look like a vector.
Humans, who are higher, have a lifespan that looks like a geometrical ray.
Note that it has a beginning point but no ending and is still monodirectional.
God, the supreme being, has a lifespan that looks like a geometrical line.
Note that it has neither beginning nor end and is bidirectional.
(Of course, that is as far as our limited minds can imagine. I have before hypothesized that God’s timeline may not be a line at all which is a one-dimensional thing, but may be a two-dimensional shape or a three-dimensional object.)
The devil then, under this model would have a ray-like lifespan: created as a byproduct but with an eternal soul.
These concepts are quite difficult to fathom, which is why I suspect the Bible never gives us a clear origin of the devil. The Bible’s goal is understandability of rudimentary truths undergirded by logical consistency, empirical adequacy, and experiential relevance - the purpose of which is to speak to the highest and lowest minds. As these matters of diabology elude comprehensibility at large, they were not fit for the Bible.