Paleo religion, acheo pharmacology and chromospectography to identify the residue in archeologic cups are subjects that you might expect I would broach.
Brian Muraresku wants to be very clear: the book 'immortality key' is not about psychedelics per say, nor has he tried them.. He’s referring to the concept of “dying before dying,” a mystical, near-death state spiritual experience.
-during a recent interview,
“Certainly, psychedelics seem to be an awfully fast-acting, reliable way to enter into that state—that state between life and death.
But it’s not the only one, and I want to be very, very clear about that.”

Still, “The Immortality Key: The Secret History of the Religion With No Name” is kind of about psychedelics. The main thesis of Muraresku’s exceptional investigative work: the modern Eucharist is a placebo variation of a psychedelic brew that originally represented the body and blood of Christ, as was likely practiced during the secret Eleusinian Mysteries. Unlike other religions and mythologies (which acknowledge prior influences), Christian leaders have remained steadfast in the assertion that Christianity emerged whole-cloth as a unique (and, in the eyes of believers, true) faith.

That’s just not how religion works. Nothing is created in a vacuum.

What are the foundations of Western civilization to Christianity? The real lineage belongs to Greece. Muraresku, who holds a degree in Latin, Greek,and Sanskrit, spent 12 years investigating this book due to his longstanding love of the Classics

https://www.youtube.com/watch?v=7c-bWymbT04 This link is a discussion among classicists on the subject of psychedelics.

The shamanic journey is a religious experience that will expose most modern western concepts of God as ridiculous and replace them with mysteries that are profound..
Being an initiated enlightened person will make them an atheist to current western religion but replace that religion with a far more spiritual understanding.
The Dionysian journey and the Elesian mysteries are being found to be from 200 million year old fungi, like Ergot rye in which beer and wine were 'dosed' as well as with psilocybin mushrooms. The ancient Greeks h ad more experience and influence from an altered state of consciousness than mere imagination and curiosity. There is a certainty in discovering who you are in the shamanistic experience that without the experience a life is only half lived. It is the experience of the God within, which has nothing to do with an egotistical view. It is not just the Mayans but it is western civilization itself that has visionary roots going back to the ancient Greeks and perhaps the Egyptians. A way to see the difference between people who have had visionary experiences and those who have not
is to compare Carl Jung and all his works and Freud. Carl Jung spent an undocumented year in Taos where he discovered psilocybin and Freud
was hung up on cocaine.
Pre Greecian civilization that has known this transcendence go back as far as Gobekli Tepi which was not a farm or temple but may have been a a brewery that made beer with rye. Was it ergotized beer? Beer residue has been found.
THERE HAS ONLY BEEN A DECADE OF ARCHEOCHEMISTS LOOKING AT ANCIENT DENTAL CALCULUS TO SEE WHAT DIET WAS EATEN. Only a few dozen are doing research. It is a new window in the archeological spectrum.

more on Brian Muraresku and Dionysian sacrements. https://www.youtube.com/watch?v=oYQh1ZNkC70
At minimum, Brian has a hypothesis worth a second look.