Do you really? If you believe in something, but don't know what it must be, then how can you believe in anything at all?

I think believing in something, is sort of admitting their might be things we do not know yet.

Which would be practically the same as saying we don't truly know. Why should the unknown always be of a spiritual nature or divine nature?

When you think hard about that, you'll see it makes as much sense as believing in God... (which doesn't make much sense.)