In March 2005, the group that became Islamic State released an explanation of its ideology,
committing itself to spreading its own interpretation of Islam and ultimately eliminating all other belief systems from the world, purifying the world by killing vast numbers of people if necessary.
Specifically, it declared:
It aims to achieve these goals through what it calls “the Prophetic methodology,” which means following its literal interpretations of the prophecy and example of Muhammad in strict detail. In many cases, it also means attempting to recreate as many aspects as possible of the 7th century world in which the prophet lived.