RIYADH - Saudi Arabia's Grand Mufti Sheikh Abdulaziz Al al-Sheikh, the highest religious authority in the country, said on Tuesday the militant groups Islamic State and al-Qaida were "enemy number one of Islam" and not in any way part of the faith.Although the mufti and other senior Saudi clerics have condemned Islamic State, al-Qaida and other groups before, the timing of Al al-Sheikh's statement is significant given the gains by militants in Iraq."Extremist and militant ideas and terrorism which spread decay on Earth, destroying human civilization, are not in any way part of Islam, but are enemy number one of Islam, and Muslims are their first victims," he said in a statement carried by the official Saudi Press Agency.He later compared them to the Kharijite movement in early Islam, which assassinated the Prophet Mohammed's son-in-law Ali for making compromises to a rival Muslim faction, and has been seen as heretical by most subsequent Muslim sects.Saudi Arabia follows the ultra conservative Wahhabi school of Sunni Islam but sees Islamist militants, who staged attacks in the kingdom last decade, as posing a threat to its own stability.