In order for your assertion to have any merit, you must show how the universe we live in can be an illusion. Go ahead and try. It is obvious that the universe is real, I am real, you are real (who are you talking to - a mirage?), and to say it is not is completely non-rational - quite out of character for a rationalist or naturalist like yourself. Perhaps you are referring to is the ultimate drug-induced hallucinatory experience...where we all find our own reality? (chuckle)
I do not assume either that matter exists eternally, not that matter exists before God. I simply ask a few questions about your position you refuse to answer. Did God make the universe and all its matter out of something or nothing? If the former, what--and how can I detect it? If the latter, how is that detectibly different than the claim that "someone imagined it up"?
Quite obviously, I believe that God created the universe ex nihilo. I still don't know what you mean by "imagined up" - what is that? If you are asking if the complex rational universe began as a thought in God's mind, I would have to say, yes, since it took 6 days. When you created your last paragraph, did you think before you wrote the ordered structure of the words?
What is the purpose of your question concerning the 4 possible explanations of the universe's existence? Something other than to simply ask a question? If you wish to withdraw this contention before the bench, the prosecution will withhold further questions.
My purpose was to show that the most reasonable explanation for the existence of a rational and ordered universe is that it was created. Since then, you have posited several non-rational possibilities. I am only interested in rational possibilities. If you can come up with another "rational" (keyword alert) possiblity aside from the 4 I gave, I have an open mind. So far, you have not done so. Berkeley is not a rational thinker - he is non-rational as he denies his own senses. Do you?
Just another way of saying, "God created the universe ex nihilo". Substitute "God" for someone, and you have Bishop Berkeley's position. Which, I point out, is, a few near-meaningless fluff words notwithstanding, identical to your position.
Contrary to your contention, there is no way to physically demonstrate that the universe is not the product of some overheated imagination, any more than it is possible to physically demonstrate that God didn't whop up the universe out of nothing. Both are immaterial ontological conjectures beyond the competence of material beings to either confirm or deny.
Unprovable is not the same as non-rational. Given that there isn't a hint of evidence either way, you have no qualitative basis for assuming my explanations are any more rational or irrational than yours.
This possibility has been explored: The Simulation Argument