Until he was stabbed multiple times with a kitchen knife and forced to flee to Europe two years ago, Asif Mohiuddin was a leading member of Bangladesh’s ‘‘freethinker’’ movement and the country’s best-known secular provocateur. We met last June at a cafe on a pedestrian promenade around the corner from his apartment, a sunlit space in a shabby-chic neighborhood in northern Germany. (He asked me not to name the city.) Mohiuddin, dressed that day in jeans and a green T-shirt that proclaimed ‘‘American Atheists Convention, Memphis, April 2-5, 2015,’’ was still getting used to the tranquillity of his new surroundings. Shortly after he secured a fellowship at a German institute and left Bangladesh, extremists serially murdered four of his friends — all secular bloggers who had criticized fundamentalist Islam and whose names appeared on ‘‘hit lists’’ assembled by hard-liners and disseminated on social media. ‘‘Everybody is wondering who will be next,’’ Mohiuddin told me while picking halfheartedly at the kiwi slices on his plate.