Thank you for your thoughtful comments.
I believe there is very good reason to postulate a spiritual realm for everything non-material in science and everything non-physical in the Bible.
There are scientists and philosophers embracing dualism to explain the subjective experience of consciousness, so I'm in good company. (Of course, they would not accept my view because it goes too far and is based on Christian metaphysics.)
Even the philosopher Kant placed mathematics outside of the physical realm, so again, I'm in good company.
In my own thoughts - it is precisely mathematics that is the outside source of things. But I include infinities in that.
It would be perfectly logical for there to be nothing. Nothing would be consistent. But clearly, things exist, instead. Why? I don't have a logical reason why there is something rather than nothing. But clearly there is something. We are here. Hmmm.
If there was nothing, would numbers exist anyway? The concept of one . . two . . . three . . .all the way to infinity? It seems to me we can't rule that out. It's not as if numbers need anything to exist.
Every word document is really a number. A great big number, consisting of all the bytes put together . . . but it takes a word program to transform it into a document we can read. And there are other ways to interpret numbers. Other programs would make alternate numbers out of a given document. Clearly there has to be a great number that would describe our universe. It would be very, very large. It would require a vast program to read it. There could be alternate numbers that describe the same universe for alternate vast programs.
The programs that would read such vast numbers would, themselves, be vast numbers being executed somehow. For numbers to relate to themselves this way - why would they even do that? I don't have a logical reason why there is something rather than nothing, either, but perhaps the solution (unknown to me) is the same here. It seems to me it might be that way.
Further, it seems to me that infinite numbers are as real as finite numbers in this context.
I've always held that God is the creator of God, and the reason this is possible is because of the seemingly paradoxical qualities of infinite numbers - and God being infinite is able to be the source of His own existence.
And this results, as a consequence, in the existence of all lesser things.
So the mind of God contemplating all things results in, as a small subset of all things, our universe.