What is a spiritual experience?
A spiritual experience is going out of your body, or remembering a past life, or perceiving something as a being and not through normal physical universe channels.
There is a big difference in knowing about spiritual experiences and actually having one. The degree of certainty when you have a spiritual experience just shoots through the roof.
It’s also intensely personal. You can’t tell someone, “You are a spiritual being”, when they think they are a body, and have it really be real to them. But if that person gets some auditing or does some training in Scientology, for whatever reason drives them (usually to improve something in their life), and they have their own adventure, then they really know.