Earlier quoted context omitted.
There is a not insignificant amount of evidence pointing to psychedelics as playing an outsized role in the formation of religions. A shaman brewing a mystical drink that gives you visions of supernatural forces is pretty convincing evidence of a god(s) to your any 2000 B.C. person. How else could you explain such a trip while having no concept of chemicals much less neurochemistry.
Alternatively you can also meditate/pray your way to similar states as the ones psychedelics induce. It takes a ton of practice, but I was able to generate very notable open-eyed hallucinations after just 2 years of low-intensity meditative practice (roughly equivalent to 120ug of LSD). It is totally believable that a true religious zealot would be able to achieve much, much more with decades of practice.
https://blogs.scientificamerican.com/cross-check/baba-ram-da...
Probably BS, but matches with what you say.