Science is inherently atheistic

[Angrboda]

For an example of something unobservable that we regularly study through scientific observation, consider the human mind. We have first person access to it, but that first person access is often not reliable and in general the mind is a black box. It's a perfect parallel because some people claim that the mind is in fact supernatural (a soul), and yet we're able to study it, make correlations, and detect patterns in its behavior. So something being more or less unobservable and even supernatural is not at all an absolute bar to scientific investigation. This contrasts sharply with something like dark matter which interacts with normal matter and energy so weakly that observation and scientific study is very difficult. So the bar that is relevant is whether it has effects upon ordinary matter and energy, not whether it's supernatural, even if supernatural is a valid thing, which it may not be.