Within a broad article by Peter Oborne, a British journalist writing in a US outlet, was this snippet, with my emphasis in bold:
This is because ISIS is not a mutation of Islam, as Obama has asserted. It is all too faithful to the literalist Saudi interpretation of Sunni Islam as set out by its 18th-century founder Muhammad Ibn Abd al-Wahhab. Hence the extraordinary popularity of ISIS within Saudi Arabia itself. According to a recent poll in the Saudi-funded Arab newspaper Al-Hayat, an astonishing 92% of Saudis believe that ISIS conforms to the values of Islam and Islamic law.

Even leaving aside my sceptcism of polling in a place like KSA we know there is support for a harsh version of Islam, not to that extent.