If there is no empirical proof for something that is logically necessary, it is sound to believe in it despite the lack of physical evidence. Logical proof supersedes empirical proof in all cases.
This was not easy to understand for someone who's not native to English. People believe in something because they need to, hence hope exists. This doesn't affect it being true or not.
We used to think something(X) was caused by physical cause and effect, but now we understand that it's caused by God, or spirits, or demons, or the soul.