Unobservable as in not existing in this universe -- not related to our tools/instruments or distance.
Okay, then responding back to your original post:
To me, I think there are only two sides of the fence you can eventually fall on in regards this.
You either entertain the idea (with varying degrees of certainty) of a Deity (theist) and continue to contemplate the significance of your role in this grand experiment ...
or you reject the concept of a Deity outright (atheist) and simply stop thinking about the unobservable how and the why altogether.
I guess then I would say that an atheist (and a skeptic) would choose not to believe in the unobservable because of their rejection of the god claim. Yes. An unobservable how and an unobservable why, would need as much (if not more) evidential support as an unobservable god. So in other words, you'd have to not only show evidence of a god, but also evidence of a purpose. So most atheists/skeptics, would choose to reject that as well.
However, take the word "unobservable" out and just leave "how and why" in your original statement...and I disagree with you. I'm in a constant state of wondering how and why we came to be here. But, I'd also have to ask, what distinguishes the unobservable from the non-existant?
So you would humor someone by talking about the possibility of a Deity, but you don't believe it possible?
Not necessarily to humor someone...but to talk about it in a hypothetical or philosophical sense. Atheists do that all the time when discussing religion.
Like discussing all the great flavors of ice cream with someone, even though you only eat custard?
Again, if were talking about hypothetical flavors (ie. Invisible and Timeless Snazzle Berry Ice Cream), then yes. I could have a hypothetical discussion about them. I'd probably tell you at the end of the discussion I didn't think that flavor existed.
Now, if you said it was chocolate ice cream. I would probably think, "well, I've had ice cream before. I've also had chocolate in other products before. So I can probably take your word on it that another flavor probably exists." And then I can just go to the store and find it on the shelf. It's too bad your Snazzle Berry Ice Cream happens to also be invisible though! Dang!
Do you believe we live in the Matrix?
Nope
"Because I haven't ruled that out.
I read a book by Brian Greene called "The Hidden Reality :.." and he covers that topic - the "Holographic Universe" theory. Crazy good stuff."
I'll have to check that one out.