Stranger In a Strange Land by Robert A. Heinlein

If you read "Stranger In A Strange Land" in either the Fawcett Crest or Berkley paperback editions (or even the earlier Putnam hardcover), then I've got some bad news for you. You didn't get to read the whole thing. The widow of the late author/scientist/inventor, Virginia Heinlein, has joined forces with Ace Trade Publishing to re-publish "Stranger" as Mr. Heinlein originally wrote it (with 30,000 words restored from the original manuscript). As good as "Stranger" was when originally published, the Ace edition reads like a completely different (and much better) book. I have the rather odd fortune (or misfortune, whichever would seem appropriate) to *live* and *work* in the area where the first half of *Stranger* is set (the area in and around Bethesda and Silver Spring, Maryland). Unfortunately, I could indeed imagine a future World Government (or even more ignominious, a US government) doing *exactly* that (large governments tend to have a "Daddy" complex, and RAH shows this better than any writer of SF).

Stranger In A Strange Land has been republished in the original unedited form by Ace (trade paperback) and G. P. Putnam (hardcover) by arrangement with the author's widow, Virginia Heinlein. So, what changed in the editing? Plenty! The restoration of the removed text adds a "wholeness" missing in the original editions (I have copies of both the original Fawcett Crest paperback and the later Berkley republishing). The thoughts of the characters are more "fleshed out" in this edition vs. the somewhat disjointed style of the original published work. Stranger In A Strange Land is still (in my humble opinion) the linchpin of the works of Robert Anson Heinlein (not to take anything away from Time Enough For Love, Methuselah's Children, or To Sail Beyond The Sunset). A lot of sacred cows (especially religion) get seriously gored in this book (warning to Catholics, especially Irish and Roman Catholics: reading this book can be hazardous to your faith). If you want a book that makes you think, then you can't go wrong with this one.

Stranger in a Strange Land is a book that lies somewhere between "good" and "very good" on a scale of "crappy" to "excellent."  The story is about a mission to Mars, during which time, two of the members of the crew have a son.  All of the people are killed during the mission, except for that son, who is then raised on Mars in the way of the Martians.  Several years later, another mission to Mars discovers that he had survived, so they bring him back to Earth.  His name is Valentine Michael Smith.
He tries to learn as much as he can about being human, as the humans he is around try to grasp the amazing things his upbringing on Mars have allowed him to do.
Skip about two hundred pages.
VMS starts a religious cult proclaiming that "You are God...and I am God...and all that groks is God."  If you are at all curious about how he reached that conclusion or what "grok" means, read the book.  I am not about to try to explain it.  Don't worry, I haven't given the ending away. 
This book is very thought-provoking, and, if you enjoy new perspectives and reading challenging opinions, you will love this book.  It is very slow in some parts, and there is no action of any kind.  About 98% of the book is dialogue, so there's really no room for it.  This is not a book for the TV generations, and definitely not for the MTV generations.  There's too much linear thought involved.  But if you're into thinking, this book can still read quickly.  It contains one of the best quotes about modern art I have ever heard (and totally agree with): "What modern artists do is pseudo-intellectual masturbation."
This book is full of that kind of gems.
By the way, as one final push for this book, Stranger has a ton of sex in it.
Hmm...might appeal to you more than you originally thought...mightn't it?