Yet what one experiences in that altered state is not proven to exist in reality. It exists merely in that individual's mind.
Yes, I was an atheist, and I would not join the Christians out of egotistical pride e.g “I'm not a Chiristian, I'm not the same as them....” sort of thing. Then I received the embrace of Ska Maria Pastora (Saliva Divinorum Godess), her embrace was semi loving and one third sexual, and it happened in the middle of the night during sleep; many, many hours after I actually smoked the Salvia. The tools of gaia work in mysterious ways I suppose. Salvia Divinorum is a decent anti fugal agent and anti inflammatory, it's more or less an NSAID but without the side effects, you ought to get some before the FDA makes illegal.
I think entheogens could perhaps lend insight into the processes of spiritual experience, so I find validity in the experience. This brings me back to... If this is your premise for experiencing a valid reality, then do you believe blind or deaf people cannot experience reality?
An alternative explanation is that your use of mind altering substances has made you delusional. Not that there's anything wrong with that, as long as you're not a danger to others. But your hallucinations don't necessarily mean that you're in touch with reality.
Since they are being equated in the thread, I think you can understand how the likely neurochemical hiccup that is a religious experience can be viewed the same way. Entheogens are essentially the same drugs as Psychedelics, perhaps including some folk herbs thay many would not view as Psychedelics. The context of the use being spiritual intent is basically what makes it entheogenic where it tries to distance itself from Hallucinogens/Psychedelics which can be more inclusive to recreational, therapeutic and other uses.
Only as an act of faith. Kant taught us long ago that humans can never be sure of the "reality" presented to them by their sense. Trust is an act of faith. I'm willing to take the leap.
Do two people ever have the same experience of life? Does that mean life is a mind altering delusion? It seems shaky at best to stipulate that because something is not reproducible, it is therefore not real we could say we could not submit it to laboratory tests, but there is much we cannot submit but consider real. For example, your emotions. This is a very slippery slope that leads to solipsism. Many things even in "reality" are not proven to exist, yet we walk around thinking about them, talking about them, even using them. The fundamental forces of and identity of "physical nature" for example, is incredibly strange and psychedelic, yet cell phones work, and light bends around gravity, even if we don't quite understand why. You seem to have an extremely materialistic view of the world, you remind me of me before I took psychedelics you see it's not that the materialistic view is "wrong" in light of an anti-materialistic view, it's that both such views miss the point. Those lost in laboratory-reality and those lost in church-reality are both missing aspects of existence. It is both. As Alan Watts said, are things fundamentally gooey (spiritual/mental), or are they prickly (physical)? They are prickly goo and gooey prickles.