It would have made for a jarring sight at any place of leisure. But the large black banners mourning the death of the Prophet Muhammad and his grandson Hasan were cause for particular dismay among the small army of skiing enthusiasts expecting a day of care-free enjoyment on Iran's slopes. The proclamations signified that the Islamic authorities had ordered the closure of Dizin, the country's leading ski resort, in memory of the religious figures, both of whom died more than 1,300 years ago. It was a mourning festival observed with passionate intensity in mosques throughout Iran. But among the affluent...