In my view(this is just my stand point)hallucinations should be viewed as hallucinations, so I prefer not to view them in any way spiritual. But I do agree with you, spiritual experiences should be a prerequisite for religiousness. Because at least in that person's mind, they've questioned, and seen proof, that god, or whoever exists. So many people don't question, and merely assume, without evidence. There's no validity either way, but still, like the saying goes "seeing is believing." Of coarse, from any logical person's standpoint, it should be seen, as I said before, as a hallucination and nothing else. EDIT: oops! Sorry for the double post!
psychedelics, in a traditional sense do not produce true hallucinations, but rather visuals or visions. a toxic delerient such as datura, would produce actual hallucinations - in the sense that you see something that is not real, but you have no idea you are tripping and take it as a solid object. the visions are manifested from your mind, drawing upon information and symbols from deep within your mind, it is personal, but also universal. it isnt the visuals that make the experience spiritual, its the quality of awareness, and the powerful removal of all previous programming that hinders us from seeing deeper levels of experience and expanded points of view. the hallucination is the ideas that society and our peers programs into us, the values that we are 'taught' are important, and mostly the view of the self as a fixed ego identity. Einstein called it an optical delusion.
"a human being is a part of a whole, called by us _universe_, a part limited in time and space. He experiences himself, his thoughts and feelings 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."
psychedelics allow you to catch a glimpse of the self removed from this "optical delusion" and the other constraints of the ego. that in and of itself is spiritual: naked awareness, a meeting with the true nature of self. a true understanding of the deep connectedness of all life. when im on psychedelics i truly feel this connectedness to everything, in a very strong way. its euphoric and transfiguring.