If we do in fact construct androids that are functionally indistinguishable from humans, it's solid circumstantial evidence for the materialist view (though not a pure slam dunk, per the p-zombie concept).

Until something like that occurs, the strongest case you can make against a transcendent meta-reality is "no one has demonstrated any reliably reproducible evidence of the supernatural."

That's a fine, solid argument for not believing in the supernatural, but it's not a great one for pronouncing that there is no such thing.