But that isn't the argument you used. Your major premise was roughly of the following form: "We don't need to postulate that x [where x is god, an alien, or what have you] is real in order to explain putative encounters with x." This logic applies equally well to "spiritual" experiences as it does to other, more "material" experiences.
In any case, those who hold that spiritual experiences point to a transcendent reality will almost always want to point to material "facts" - immutability, stigmata, or any other among a variety of alleged spiritually-grounded physical phenomena - to buttress their claims. But such claims, of course, invite the very same questions regarding the reliability, veracity and interpretation of given physical facts.