joelingeorgia wrote: "nothing exists except the natural universe."
OK, let's assume that is true. Nature provides numerous examples that all natural things that exist had a definative beginning. Even the present natural universe is said to have been a ball of particles the size of a basketball when it began with a big bang. Yet, those natural particles must also have had a beginning.
Where did the particles (or the energy) come from? If the particles (or energy) always existed and always will exist, then they are eternal, and self-existant, that is, unnatural or supernatural, for there is nothing else like them in the nature that we can see and experience. Our experience indicates that energy dissipates from useful heat/work to absolute motionless cold. Particles/energy does not go on eternally.
Whether you believe in a supernatural self-existant God, or in a supernatural self-existant universe of particles (or energy), to say "nothing exists except the natural universe" really does not answer any genuine question.
The eternal self-existant does exist beyond our ability to see or experience. That is the very definition of supernatural.