A student at the Art Institute of Portland, a for-profit institution in Oregon, says he was expelled because he is an atheist. The student, Bob Averill, told The Portland Mercury, a weekly newspaper, that administrators had dismissed him after another student complained that he had attacked her religious beliefs during a class discussion. In a letter to Mr. Averill, an administrator said the student had violated the campus’s conduct policy, citing a series of incidents in which Mr. Averill’s actions were “aggressive, demeaning, and threatening,” the official wrote. Mr. Averill, who runs a blog called the Portland Atheist, has contacted the American Civil Liberties Union about his dismissal.