Islamic fundamentalists posted death threats against a Polish disk jockey soon after he published a song that he says was supposed to be a tribute to the Muslim culture. It started on Christmas Eve. Jakub Rene Kosik, a 27-year-old DJ from Poland excused himself from the dinner table and checked his Facebook. Word of his newest composition, Mekka, was out. And it was ill-received. “You messed with Islam,†the first message read. “We’ll never forgive what you did to our religion,†read another. “You played with us, now we’ll play with you.†“We’re everywhere. Forget your international career.†By morning...