Some say that spiritual connection or a feeling of oneness can be known through meditation. So it doesn't have to be just a belief in someone's mind but something that is tangible on a subjective level. Some have near death experiences that touch them and change them dramatically, like brain scientist Jill Bolte Taylor who survived to tell her story. Then there's quantum physics. The two slits experiment shows how observing (or not) the experiment affects the end result. Suggesting that there's some connection between the observer and reality. Considering that all that is physical came from the same dot of energy (ie The Big Bang) the theory that all is still interconnected on some level, is not that far fetched. After all our senses and measuring devices are only capable of interpreting a small portion of the electro-magnetic spectrum. I'm agnostic but really enjoyed Eckhart Tolle's books. The best description of spirituality I've read after the following Einstein's quotation: There you go, plenty of subject suggestions for future podcasts : )"A human being is a part of the whole called by us universe, a part limited in time and space. He experiences himself, his thoughts and feeling as something separated from the rest, a kind of optical delusion of his consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty."
I think you should revisit your interpretation of reasons double slit experiment. The observer for example does not need to be. conscious or human in order for the duality to become apparent. More importantly the phenomenon shows a divide between classical physics and behavior at the quantum scale. Giving an experiment the ability to decide or otherwise prove consciousness is dangerous.Then there's quantum physics. The two slits experiment shows how observing (or not) the experiment affects the end result. Suggesting that there's some connection between the observer and reality. Considering that all that is physical came from the same dot of energy (ie The Big Bang) the theory that all is still interconnected on some level, is not that far fetched. After all our senses and measuring devices are only capable of interpreting a small portion of the electro-magnetic spectrum.
I think the interpretation is up for debate. Classic science doesn't like the word "consciousness" because it's not something tangible but it is an undeniable part of our experience and sooner or later we'll have to agree on how it fits in our perceived physical reality. Here's how a couple physicists interpreted it. Nobel Prize Winner physicist Eugene Wigner said: The very study of the external world led to the conclusion that the content of the consciousness is an ultimate reality." Another physicist's word, Werner Heisenberg:"When the province of physical theory was extended to encompass microscopic phenomena, through the creation of quantum mechanics, the concept of consciousness came to the fore again: it was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to the consciousness.
"Natural science does not simply describe and explain nature; it is a part of the interplay between nature and ourselves; it describes nature as exposed to our method of questioning. This was a possibility of which Descartes could not have thought, but it makes the sharp separation between the world and the I impossible."