You mean you want us to prove a negative?
Arguing from ignorance?
That's how most of his kind works.
We have never seen or experienced any immaterial thing. We may not be able to do so. Yet in his mind, we must prove that these things don't exist, anywhere.
So, for that matter, invisible pink unicorns, faeries, and dragons are all real, too, until proven otherwise.
I think we've proven beyond reasonable doubt that stillthinkin' lacks, severely, in reasoning faculty, and is unfamiliar with the modern state of science or philosophy. Yes, I know, ST - ad hom. Big whoop. The fact remains, your premises are unsound, and your argument is invalid.
Show me the immaterial elements to the human. I can show you the material ones. Until you can do the first, we must assume that humans are material beings.
End of argument.