The phrase "stranger in a strange land" has been around since the early biblical translations into English began (Exodus 2:22.) Growing up, I'd heard of the book often and of course heard of the songs of the same title by Iron Maiden and Leon Russell. Recently, the text was placed in my hands (ok, it was a bag stacked full of books) by Teri and Lloyd, I was just an egg.
You see, the book's main character is a human male named Valentine Michael Smith who was born on Mars under the supervision of Martians and has returned to Earth as an adult. In the early part of the book, Smith becomes the perfect vessel to examine the human condition through the eyes of someone just learning (or who is "just an egg.") We've seen this type of situation used often with Star Trek: TNG's Data, Star Trek's Spock, Tom Hanks in Big and Darryl Hannah in Splash (well, that's more of a fish out of water tale.)
Another point that I find fascinating at the start of the book is Heinlein's view of the 'space race' in the early 60's. The book was published in 1961 during the same year that President John F. Kennedy said, "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project...will be more exciting, or more impressive to mankind, or more important...and none will be so difficult or expensive to accomplish...." We hadn't reached the moon yet but Heinlein saw us hitting Mars. He also believed the Russians would get there before us.
The first half of the book deals with Smith's becoming accustomed to Earth, his "rights" as a human, his money (as sole heir to a fortune) and to the correct uses of his extraordinary abilities. The second half makes a jerky right turn and proceeds into making Smith a pseudo-Christ character as he creates a cultish 'church' in an effort to educate the masses. Of course, problems arise with rival factions, organized criminals and a frenzied media. I really started losing touch with the book when they brought angels into it and then revealed Smith's true character...
No more for spoilers but if you haven't read the book, it is worth it as he creates some great characters whose interactions are absolutely hilarious at times (had me laughing out loud at work.) Most of these involve the character Jubal Harshaw (an educated older eccentric millionaire and reclusive writer) who will remain a favorite. Also worth noting is that Heinlein coined the word "grok" in this book which means to drink, to understand and to be one with.