Disclaimer: this is just my own thoughts, and is NOT meant to be me presenting what is objective unquestionable fact.
In my view, mathematical facts are, somehow, more primal than just about anything else. Any physical law, you can imagine a universe where that law is different. Perhaps you can imagine a universe where gravity is weaker, or is nonexistent, or even repellant rather than attractive. You can imagine a universe where various physical forces are stronger or weaker than they are now.
But in all of those universes, certain mathematical truths remain true.
I believe that mathematical truths are the deepest primal truth, and if there were a God, the mathematical truths would be even more primal and unbreakable than him.