Islam is on its way to become the most practiced religion in Europe. In a new book published by the University of Leuven, “The Iris and the Crescent,” sociologist Felice Dassetto says that Muslims will comprise the majority of the population of Brussels by 2030. The title of the book refers to the yellow flower symbol of Brussels’ region and to the Islamic emblem: While the first is decaying, the second is growing. Muslims now make up one-quarter of the population of the capital of the enlightened Europe and they are asking to use the empty churches for Islamic prayers....