No individual or organization or state follow Islam as accurately as IS or Islamic State. Muhammad Killed non-Muslim men and used their girls and women as sex slaves. IS guys did the same. They killed Yazidi men and held Yazidi girls and women as sex slaves.
Islam always advise Muslims to do everything what Muhammad the prophet did. Eventhough Muslim men love their prophet, it is extremely rare that they marry 13 times or marry a 6-year-old girl or their daughter in law. It is IS that shows the courage to behave like true Muslims and adapt the character of the prophet. The prophet loved swords or knives to kill people, IS does the same. The prophet treated women as sex slaves, IS does the same. The prophet occupied land by arms and violence, IS does the same. The prophet destroyed non-Muslims’ temples and sculptures, IS does the same.