If Facebook were a religion, it would be the second largest in the world

Facebook announced last week that 2 billion people – more than one quarter of the world’s population – are now active users of the social network Mark Zuckerberg started in his dorm room 13 years ago.
Two decades ago, the notion that billions of humans would be connected by a single product would have been seen as absurd, unless the “product” in question were, say, a religious text. But now Facebook has more adherents than any religion in the world, with the excepti