So, I suppose the key here is the personal experience.
I'm sure there are a lot of ways people can have deep spiritual experiences without them interpreting it as communicating with divine forces.
The one thing I am tying to validate / invalidate is weather "spiritual" as used by non religious people, is mere hacking of our delicate physical and chemical machinery.
I don't know, but I have a gut feeling the spiritual awe one gets from one religious sacrament or another and getting it through other means are the same thing.
Effectively, the way I see it, religions claim something that is universal and publicly available as under their domain. It's like a guy came and wanted to resell the air you breath back at you.
Similarly I feel drug afficionados are sometimes overselling their hobby as the one key to the mysteries of the universe.
I don't mind if someone is religious or likes to do drugs. What I don't like, is that one or another claims something that can gained by other means as belonging to their dominion.
The major religions are especially intransigent and arrogant about this in their creed - claiming things that belong to all men and women to belong only to one sect or another - thus poisoning themselves doubly by first trying to fool those outside of their creed, and then being intellectually dishonest of their own experiences.
It really is, if our minds are entirely a manifestation of the brain.
Is it just the perspective of the one who has the experience? As Tim Leary said: The caterpillar cannot understand the butterfly.
This was some two decades ago. I've never felt anything like that after that, but the memory of the sensation is still very strong.
No drugs. Just the most basic 'lie-down-relaxed-and-watch-at-a-dot' exercise. And wham.
It was pretty cool. I was an adolescent back then and I had decided several years before that logically religion was total BS. Had I been religious I'm sure I would have interpreted my experience as being in direct communion with God. But, I interpreted it as a neurological response to my meditation - which did not make the experience any less spiritual.
The experience did not reveal anything new to me, but it made me feel the truth that we all are one and connected, philosophically speaking.
Feeling is something purely logical discourse seldom provides. This experience was pure feeling. Like, I intuitively feel my legs are part of me. I felt the whole world was part of me. Now, this is at the same time true - or - false. We are made of the same atoms and are interconnected through our actions and the laws of physics. At the same time, it's a bit silly to describe oneself extending beyond ones body. So, one can choose was I enlightened by a fundamental truth or was I just a bit silly after a brief session of neurohacking.