PARIS — A hundred years ago, Paris erected a monumental mosque to honor Muslim soldiers from French colonies who fought in World War I. It’s now an integral part of the capital’s bustling Latin Quarter, and as it celebrates its centenary, worshippers are reflecting on being Muslim in today’s France.The rector of the Grand Mosque of Paris sees it as a symbol of interfaith dialogue and France’s diversity, but worries about religious tensions in the country linked to conflicts in the Middle East and the polarizing campaign for next year’s presidential election.“It’s the responsibility of everyone to see Muslims as...