Social media helped Paul build a church; in the hands of Martin Luther, an obscure theologian in the German town of Wittenberg, it helped to split Western Christianity.
Luther hadn't expected his "95 Theses" - a handwritten list of theological challenges to the Catholic doctrine of indulgences, which he proposed as topics of debate in 1517 - to spread as quickly as it did. Manuscript copies of his pioneering listicle passed from hand to hand at first, but then printers got hold of it, accelerating its spread and making it the talk of Germany within two weeks, and of Western Europe in four. Luther realized he could use this new technology, invented a few decades earlier by Johannes Gutenberg, to his further advantage.
He followed up with a series of pamphlets written in vernacular German, giving the text of each to a printer in his home town and waiting for it to ripple to the next town, and the next, through repeated reprinting (akin, you could say, to retweeting). Millions of copies of his pamphlets spread like wildfire throughout Europe between 1517 and 1527 as readers shared and recommended them to their friends, who then sought out their own copies. Thanks to the "marvellous, new and subtle art, the art of printing," one of Luther's contemporaries later noted, "each man became eager for knowledge, not without feeling a sense of amazement at his former blindness." This posed a dilemma for the Catholic Church, which was initially reluctant to respond with pamphlets of its own, because doing so would be an admission that theological matters were open to debate. The extraordinary popularity of Luther's pamphlets signaled to him, and to his readers, the breadth of support for his views - just as social media revealed the extent of anti-government feeling in Egypt and Tunisia, a phenomenon that modern media scholars call "synchronization of opinion." Luther's message went viral, and the result was the Reformation.
3. John Harington