A minor issue at the Minneapolis-St. Paul International Airport (MSP) has potentially major implications for the future of Islam in the United States. Starting about a decade ago, some Muslim taxi drivers serving the airport declared that they would not transport passengers visibly carrying alcohol, in transparent duty-free shopping bags, for example. This stance stemmed from their understanding of the Koran's ban on alcohol. A driver named Fuad Omar explained: "This is our religion. We could be punished in the afterlife if we agree to [transport alcohol]. This is a Koran issue. This came from heaven." Another driver, Muhamed Mursal,...