Foot prints, prey bones, etc. You are getting tired. A physical being will leave evidence. See if when you walk around its "lair" if you walk into huge piles of invisible poop.
One can also test, like they do with psychic powers the hypothesis of "magic", to see if you can replicate it or cause it to repeat consistently. See whether or not nearby stock animals disappear to a roar from a creature they can't see. Does it find virgins particularly tasty? Yeah, somebody could test for such a thing if there were any physical evidence at all.
If the creature existed, and evidence could be collected, like Sasquatch, you might even get a group of people to believe that it existed.
Now again, how do you test for a Supreme All Powerful, all knowing, being that doesn't follow any of the laws of physics and isn't tangible in any way?
God is outside of science because it is untestable. If you cannot devise a reliable test of any sort, it is outside of any ability for the scientific method to prove or disprove. It is impossible even to collect evidence other than that of anecdotal nature.
It's untestable to our current science. God could very well exist within the realm of science, but merely be untestable without further advancement of our methods.
Getting back to the original topic of the thread; perhaps the wording is a bit harsh, but at what point would such a belief be embarassing for you? Would it be embarassing, say, if most of our politicians believed that the earth was 6,000 years old? Would it be embarassing at all if our educational curriculum was changed to reflect that, or if children were taught that no physical science or scientific conclusions were reliable, because it's possible some higher being was involved in some way that either made it illusion or otherwise impossible to trust our own senses?
What would that say to the world? What would it do to the field of science?
Now, none of this is going to happen, but I think it gets into a pretty fuzzy, risky area when we start trying to minimize science & the scientific method by inserting the God variable, thus undermining every conclusion that we've ever learned about the earth & the universe (which is basically what you've been doing).