Well, the thing about religion and spirituality is that, by the very nature of the subject, it is very difficult to "teach." It's not like science, where you can recreate and show experiments and have models and equations to explain it if the conceptual stuff is too hard to explain or understand. There are scientific ways of explaining it, but the nature of the subject is inherently different from science, so that only goes so far.
It's like trying to explain a feeling. Or an intuitive understanding of something. Like me trying to explain to my ESTP friend why I get depressed when it seems like my life's "easier" than his, or explaining how something tastes to someone who has never tasted anything like it. You COULD do it, but it'd be really difficult.
Spirituality is a personal thing; it's something you have to come to understand and experience yourself before you really can understand the topic of why people are into it and how it transcends cultures. There's more to religion than just a bunch of rules; that's actually more of a culture thing than a religious thing, I think. You have to take religious word with a cup of tea; even if it was "divinely inspired" as people think it was, it was still recorded by people, so it could still be culturally influenced. But the core spirituality, the reason for spirituality transcends that. And that's the part that's hard to explain; rather than approaching it like science, where you see the outline or rules and assume that's the end result of what you're supposed to get out of it, you have to approach it like you're approaching a complicated person, because it's a social thing. It's a human thing, not a logical thing; you can't explain spirituality with science accurately.
In other words, the Bibles, books of worship, and rules are just the beginning. It's the starting point; many people don't realize that you're not working towards just going through the motions, but rather that you have to search for what it means to you and how you can reach "enlightenment" through it. It's not easy; it's not simple; it's not concrete. You have to approach it differently.
And that's what that article I quoted from touched on; an idea of a single, Primal knowledge that we are searching for, that's different from physical knowledge; it's a spiritual knowledge that people are drawn to. It's not just replacing what you can't understand; in fact, I'm not even sure if it brings any real "answers." It brings a true contentment, and understanding of not being able to understand, and an acceptance of something greater than yourself, whether that be a God, gods, or just the energy of the universe. That's spirituality; that's the basis of religion; and that's really hard to explain or prove.
