I don't know that it's possible to prove spirit, but most of us seem to have it. Faith isn't a fallacy, and we can never prove spirituality or many other things that are powerful forces in the universe. Respectfully, I disagree with your thought that it must be proved to exist. I can understand that you mean it to be applicable to yourself only, however.

In a lighter sense, science has never been able (to my knowledge)to prove the existence of telepathy, but those who have experienced it know it to be a valid phenomenon. The analogy is similar to spiritual reality and both are esoteric, probably.

This subject, Landskaperdan, is necessarily a controversial one, but
I think everyone is trying to offer an explanation for you that helps you
begin your search for spiritual development. We are all growing in that
respect throughout life, in my view.