I just finished a book called The Year of Living Biblically by A. J. Jacobs. If I knew how to hyperlink, I'd send you to Amazon or something to see what the book looks like, but alas, I am very ignorant when it comes to doing stuff like that, so you'll have to find it yourself. Sorry!
Anyway, the book is about the author's quest to live by the Book, the Bible, as literally as possible, for a year. He wears white, doesn't eat shellfish, does unto others, etc. But by the end (spoiler warning here!), he still refers to himself as agnostic, saying that he has changed in that now he believes in the sacredness of things, but doesn't know whether or not there is really a God.
This got me thinking: can there even be a sacred if there is no God? If sacred means set apart, then yes, sacred and common can exist. That is, you can have the "set apart from" but you certainly can't have the "set apart to" unless you set it apart to a person or mankind in general.
It was sad though, the ending of this book. The author read the Bible thoroughly, probably knows it better than many Christians (to our shame) and yet at the end of his year, he was simply a better person.
However, I must say that I enjoyed this book completely. It is well-written, snappy, funny, and makes you think. I recommend it!