Both Uses

mystic
in
Nine Stories
(Auto-generated)

I'm about to touch on an extraordinary experience, one that still strikes me as having been quite transcendent, and I'd like, if possible, to avoid seeming to pass it off as a case, or even a borderline case, of genuine mysticism.†
Story 8

mysticism = belief in realities that are outside of scientific understanding and normal experience
I believe you said on that last tape that you were six when you first had a mystical experience.†
Story 9 *

mystical = relating to realities beyond scientific understanding OR inspiring a sense of wonder or mystery; or beyond human comprehension

Definitions:

(1) (mystic)
a person who seeks or claims to have direct spiritual insight beyond ordinary understanding; or describing an experience that feels deeply spiritual, mysterious, or otherworldly

In common usage, mystic is more likely to be used in reference to a practitioner of a less mainstream religion than a more mainstream religion -- possibly because the former is more mysterious to the writer.
(2) (meaning too rare to warrant focus)