Materialism has plenty of awful side effects like hubris, nihilism, and anti-natalism.

...perceptions of omniscience.

The words you're saying aren't materialist so much as they are logical positivist. As it turns out, there are things that are both true but not provable (be it empirically or analytically).

Prove it.

Spoken like a positivist. Here you go: https://plato.stanford.edu/entries/goedel-incompleteness/