Spiritual experiences have been studied scientifically but all that can be proven is that an individual's CNS chemistry and electrical activity in the brain changes, which is basically all that is true for the scientific study of sensing and perceiving pain and pleasure. The link between the physically measurable and the mental/emotional states is still unexplainable other than to say that it is subjective and experiential. At that point it has to be accepted that the link exists, which is the same as faith. It can't be proven with physical evidence but we believe it is real because our experiences show us that it is.