Both the Hitchhiker's trilogy and the Dirk Gently books (all by Douglas Adams)
There are no such things as sacred texts.
That's the joke. :) I think if you're on this site you probably know that.
The God Delusion by Richard Dawkins, all of Bart Ehrman's books, God is not great By Christopher Hitchens, George R. R. Martin's books, Carl Sagan's A Demon Haunted World just to name a very very few.
All good ones!
The audio book version of Darwin's "On Origin of Species" is narrated by Dawkins, and is a fascinating kick to the head.
Leaving out the words sacred and worship, two of my favorites are "The God Delusion" by Richard Dawkins and "Under the Banner of Heaven" by Jon Krakauer.
Personally, if you want a good story, you can't beat the Odyssey. Also, Penn Jillette's "God, No" is pretty good.
Has To Kill A Mockingbird been mentioned?
Also, The Universe in a Nutshell. :)
In don't worship books.