 In most traditions, the Mahdi will arrive with 'Isa (the Muslimised Jesus) to defeat "Al-Masih ad-Dajjal" ("the false Messiah", or Antichrist).Although the concept of a Mahdi is not an essential doctrine in Sunni Islam, it is popular among both Sunni and Shia Muslims.Both agree that he will rule over Muslims and establish justice; however, they differ extensively on his attributes and status.