There is international agreement that no one should be made stateless. That's all well and good however ISIS has declared itself a 'state' and does not rely on recognition by the UN or any countries. There is no tribunal that can green light the formation of a 'state'. So those who cleave to the ISIS doctrines, policies, goals and ambitions would seem to belong to a state.
Islamic State of Iraq and the Levant
The Islamic State of Iraq and the Levant, also known as the Islamic State of Iraq and Syria, officially known as the Islamic State and also known by its Arabic acronym Daesh, is a militant group and former unrecognized proto-state that follows a Salafi jihadist doctrine. https://en.wikipedia.org/wiki/Islamic_State_of_Iraq_and_the_Levant
