Does a mushroom high necessarily feel spiritual? Do those feelings last past the high? How much do your beliefs change, if they change at all?
No drug is "necessarily" anything to everyone. I've had mushroom trips that did not feel spiritual but just felt deranged and dark but that was largely a set and setting issue. Actually I can only think of one time that happened... the other times all had a definite "spiritual element" although I think you really need to define spiritual here, I'll loosely define "feeling spiritual" as meaning "granting the perception that there is a metaphysical reality which we usually cannot access but which is tangible and real and significant in some nebulous way, not just mystical hokum", lol OK so that definition was longer than I planned but the vast majority of my shroom "highs" have had a definite "spiritual" component. I didn't always recognize these as "spiritual" at the time though, when I was younger definitely all my trips were mostly hedonic pursuits and I've tripped while being somewhat militantly atheist and materialist, and back then the words I'd use would be "epic", "profound", or honestly sometimes just a bit too confusing to think about the spirituality of it except that it was something fairly "magical" in that it made me question the nature of reality somewhat... for whatever reason more recent trips I've been more inclined to think of as "spiritual", in fact they had an
overtly spiritual component featuring feelings of being in the presence of the divine being and suchlike. So... yeah actually no I'd say a mushroom high does not
necessarily feel spiritual, although as far as psychedelics go which are all
more spiritual (as in, more likely to induce experiences that people think of as "spiritual") than other classes of drugs, psilocybin mushrooms I'd say are up there as some of the most spiritual drugs of the most spiritual class. But that doesn't mean that everyone will experience every trip as a spiritual one. A more consistent descriptor would be, again, a word like "profound", but even this is not guaranteed, a trip could still be just confusing and frightening. I'd venture to say that positive experiences would be far more likely to be coupled with profundity or spirituality just because even if the trip is just "epically fun" that has the effect of kinda opening one's mind to the inherent profundity of the psychedelic experience - which is present, I'd say, even on an aforementioned darker trip, it's just that the natural tendency is to kinda try to shut oneself off from all the frightening shit when it gets scary and thus harder to appreciate those things.
Do those feelings last past the high, sure, they can do, although they might not. Actually let's clarify the question here a bit... if one has a
spiritual experience on mushrooms then I'd say yes, some of that will last beyond the high, it's kinda unavoidable because it's the nature of a spiritual experience or a certain degree of abstract profundity that these are big enough feelings to impact the person feeling them, otherwise it's kinda questionable if the experience really was all that profound if the high wears off and you're just like huh that was cool but then immediately forget about it and go about your day. Maybe it's not impossible that someone would have and when they come down don't feel any different to before they dosed, but it would be unusual, I feel like the profundity and neuroplastic changes induced by heavy psychedelic trips are probably tightly coupled, and the only instances I can really think of where they don't have a significant perceptible impact would probably be in a mind/brain that's already close to some kind of experiential/developmental extreme, ie, a monk whose daily meditation practice is recognisable on a brain scan and who for all intents and purposes is "enlightened" already, whatever that means, OR some unfortunate person with some severe brain pathology which makes them so apathetic they just can't connect to the experience they've just had. But I think honestly you'd know if you were this kind of person, these would be states with significant impact on daily life for the most part. I guess there might be some freakish genetic outliers living normal lives able to both fully experience and entirely weather the impact of a heavy dose of shrooms unbothered after the fact though... it's not impossible, for sure... but, unlikely.
How much do beliefs change, really varies, for some people a lot, for some people not at all. If you have a profound spiritual experience that stays with you after the fact it would be strange if it didn't affect your beliefs at all though, so, kinda the same deal as the last question, IMO, if a little more variance just based on the fact that it's possible to be cognizant of the fact that you had an experience indicative of the existence of a metaphysical realm while knowing that there's no way you can really tell if your desire to believe in the reality of your perceptions - even under the influence, to an extent - should override the knowledge that what you experienced was most definitely not part of consensus reality and thus you can't really draw any conclusions from that. But even this experience of a mild cognitive dissonance and the fact that you're even asking yourself that question should make you a bit more humble about what you do believe, in most cases. But again, really depends on the person.