Oh, come on, don’t groan. You knew that was coming.
In a negative way - in terms of the scale of death and destruction inspired and foretold by a single book - I’d say Mein Kampf.
Of course a lot of killing has been done in the name of scriptures too.
Newton’s Principia, one of the chief foundations of modern science. That and Bacon’s treatise that contains the Scientific Method.
I’d argue against Mein Kampf on the grounds that it didn’t really have much influence independant of Hitler himself. I think more of Hitler’s followers were inspired by speeches, newsreels, other propaganda, and the general currents of public opinion than ever actually sat down to read the book.
My knee jerk reaction on reading the topic was The Communist Manifesto just because it has perhaps the best documented chain of ideological descent. But as I think more on it, one could argue that it is, ironically enough, biblically inspired, at its core.
I’d rate the Koran (I prefer politically incorrect, anglicized spellings) over the Bible in terms of the influence of its actual content, inasmuch as it seems much more specifically prescriptive in terms of conduct and doctrine. Of course, in both cases more has tended to be done in the name of the book than in actual adherence to it, but I guess that comes under the “influence” heading as well.
How about Lives by Plutarch
We haven’t felt their full effect yet but I still nominate the entire Left Behind series of masterpieces 
I’d say the bible. It has guided the actions of many European nations for centuries. Over the past 500 years, the western nations have, using much of the bible as a reason/excuse for most of that time, disrupted the entire planet.
- Bible
- Koran
- Scientific Progress Goes ‘Boink’.
Number one is easy, The Bible.
For number two, I nominate Dr. Benjamin Spock’s Common Sense Book of Baby and Child Care. Sales have averaged about a million copies per year since its first publication in 1946. What could be more influential than a book about raising children? Especially when that book was probably the blueprint for the upbringings of about one in five of us (conservative estimate).
“Trust yourself.”