To what end?
Can you prove the taste of an orange? If someone is intrigued by your description, then they may wish to try tasting an orange themselves. But without tasting it, there is no proof of its taste possible.
This is strange to me. The taste of an orange is neither true nor false. Even to say it tastes good or bad isn't a matter of truth or falsity, although at least those can be opinions.
So I don't see anything to 'prove' about the taste of an orange.
The spiritual is something that is either attractive to someone, or it doesn't garner their attention. That's their path. Like the old saying, you can lead a horse to water, but you can't make it drink. The only proof of the spiritual is actual experience. Not a theory about oranges.
If the goal is to have experiences, then the goal is not truth. That's OK. I like to have experiences also. They are just different from truths. Now, truths can be based on experience through interpretation, hypothesis formation, and testing. Beliefs are also the result of experiences, although usually with far fewer controls and much more subjective than truths.
It just seems strange to me to identify an experience, in and of itself, as having a truth value. The *interpretation* of the experience may well have a truth value (if it goes beyond opinion).
So, I may interpret the wild feeling I get in some circumstances as 'being touched by the Flying Spaghetti Monster'. Whether that interpretation is correct or not depends on whether FSM exists and whether I was, in fact, touched by that being.
But, even if I don't interpret the experience correctly, I still had an experience.