re: Eastern Bishops demand Muslims issue fatwas condemning ISIS, etc.

Well it wouldn't do anything because Islam isn't a monolithic group. In the Sunni sect, there are four major schools of jurisprudence, and each have their centers which would issue fatwas. ISIS is a Salafi group, and they would have no reason to take anything said by anyone other than someone in that movement seriously. As for Shias, the Ayatollah's in Iran and Iraq can issue fatwas, but ISIS and other Jihadist groups that developed from the Salafi's, Deobindi's, and followers of Sayyid Qutb have no reason to take those opinions seriously.