Stranger In a Strange Land by Robert A. Heinlein isn't your stereotypical science fiction novel. It is a novel that leaves the reader thinking about love, their own life, and ethics; therefore, I would only recommend it for the philosophically inclined.
Although under the most straightforward interpretation of the title there is nothing ambiguous about the words 'stranger' and 'strange', there is an alternate interpretation that I would like to proffer. Under the straightforward interpretation, the stranger is Valentine Michael Smith -- the man from Mars -- and the strange land is earth.
Alternatively, one can interpret the word 'stranger' in the title of this novel to relate to any human living on earth who is not accustomed to the Martian way of life, an unenlightened individual. The 'strange land' would then refer to the very same Earth -- a very strange place for the unenlightened human. Under this interpretation, I am using the "One who is unaccustomed to or unacquainted with something specified; a novice." definition of 'stranger' and the "Not previously known; unfamiliar." definition of 'strange'. These definitions were taken from the 'stranger' entry on dictionary.com.
This novel does a good job at showing how non-Martian lifestyle-following, earth-dwelling humans are novices in the game of life. The stranger is the human who has grown old and weary in his ways by adhering to the tenets of modern society. The novel shows how such a non-Martian lifestyle leaves one unfamiliar with respect to the taste of reality. The man from Mars handed out a taste of Utopia and the strangers were the humans who haven't yet shared water and grown closer. Perhaps Heinlein wanted to convey the idea that the strangeness of the world around us is intimately related to our world view; Mike wanted to make the world less strange for the denizens of Earth.
Ahead of its time (this book was released in the early 60s and not the early 70s) and promoting a pantheistic view that emphasizes personal responsibility in our own lives, this book is not only entertaining but it will leave the reading asking questions.