ISIS leader Abu Bakr al-Baghdadi has released a call to arms which asks Muslims everywhere to physically join ISIS in the area it now controls or simply take up the struggle against unbelievers wherever they are. The title of the message "March Forth Whether Heavy or Light" comes from a verse in the Koran which calls on believers to "strive with your wealth and your lives in the cause of Allah." In Baghdadi's view that striving is ISIS's war against unbelievers. "O Muslims, Islam was never for a day the religion of peace. Islam is the religion of war," al-Baghdadi...