I hate to agree with you, The Bible has unfortunately influenced far more people than Chalie, but I would argue that Darwin's theory of Natural Selection outlined in The Origin represents the largest conscious step we Homo sapiens have taken. And thus it is important!
I am not disagreeing that Darwin's theories aren't important, but as far as his book being the most important book ever written I'd have to strongly disagree. Most religious texts would be considered by the world as far more important and having influenced far more people, and whilst Darwin's theory changed the way we think I don't know whether it is the "largest conscious step we have ever taken."