Here is an old article regarding the mystical effects of psilocybin.
According to the Baltimore team, nearly two-thirds of the volunteers said they achieved a “mystical experience” with “substantial personal meaning.” One-third rated the psilocybin experience as “the single most spiritually significant experience of his or her life,” and another 38 percent placed the experience among their “top five” most spiritually significant moments.
When I encountered this, I was underwhelmed by the unsatisfying epistemic bases for framing this issue as “spiritual experience” and evidence or not for something or the other. [To me, it seems simply enough an issue of psychoactive drug effects, and is evidence for nothing other than a blown mind.]
The language of memetics provides a “simple” explanation for this, however: The “psychedelic/mystical” memeplex and the “spirituality” memeplex are coevocative and hence can cooperate advantageously. [The complexity in the explanation is of course hidden in the meaning-laden word “meme”.]