By Laura Bates Sourcebooks ; $28.99 ; 352pp There’s an ideology that’s spreading via the internet, leading to terrorist attacks in America. It existed before the internet of course, but the past decade has seen it spread rapidly through mobile social media, growing in both breadth and virulence. Of course for an ideology to convince a score of men to commit mass murder in suicide attacks on the U.S. mainland you would expect there to be a sizeable number of less fanatical supporters. And that is indeed the case. Anyone who doubts the mass influence of this ideology only has to look at the...