The title of this thread "Top 25 Books that Changed the World"...
It's subjective, but at least "Top" does denote some level of admission of Opinion ("Top" ends up equally "Best" or "Favorite".)  For instance, like it or not "Mein Kampf" "Changed the World". 

For iris's allusion, I'd narrow the answer to Gutenberg's Bible.
Also there's "The Communist Manifesto".  (I recently some essays from a collection of "The Marx / Engels Reader". I'd point to a few key selections as things you should read-- pieces on Napoleon, the Paris Commune, and the Revolutions of 1848.  A lot of other essays I just skipped over, I admit)

We restrict "Changed America" you get to something like "Uncle Tom's Cabin" and "How To Win Friends and Influence People".  (Though maybe they've had enough influence worldwide to warrant consideration for a list?)  Also Henry David Thoreau's Civil Disobedience.