LONDON -- Leaders of a key Muslim organization in Britain, angered by the deadly terror attacks in London, yesterday told tens of thousands of followers that "enough is enough" and urged all Muslims to turn away from "harbingers of hate." "The word 'Islam' means peace," said Rafiq Hayat, national president of the Ahmadiyya Muslim Association U.K., "but we have to live by it in order to grow." Mr. Hayat's call for Muslims to quit listening to fanatics who stir terrorists to action came in the wake of a new opinion survey showing that one in four Muslims in Britain sympathizes...