You made my exact point at the end.

“We don’t know” is not a statement of faith or belief.

I don’t know how how my phone works. That doesn’t mean I believe in Android or Samsung. Humanity doesn’t understand why the expansion of the universe is accelerating, but that doesn’t make the reason for the acceleration a matter of faith. It’s simply a gap in knowledge.

Knowledge is the realm of fact. Belief is the realm of the unknowable, not the unknown.