KBF. Quite right on the Wahhabi sect, though it is embraced as the state religion of Saudi Arabia. (Presumably Sunni rather than Shia in view of that).
It's an incredibly 'stripped down' and fundamentalist version of Islam, rejecting all modernising influences within Islam, seeking to return to a probably mythical golden age of simplicity and certainty. It relies on short prayers, undecorated mosques and extreme hostility to mainstream Islam, and to any form of Western influence, corruption or decadence. Wahhabis punish anyone who enjoys music (other than the drum) and condemn those who don't pray as unbelievers. It's almost tailor made to appeal to desert arabs, and in doing so, also appeals to today's demand for simple solutions (hence the rise of fundamentalism in so many religions) They are, if you like, Islam's protestant puritans or bolsheviks, and will not write the name of Mohammed or celebrate his birthday. They would claim to be 'better' and purer Moslems than followers of mainstream Islam.
It's relatively new, though, Ibn Wahhab (the cult's founder) having lived during the 18th Century. Historically it espoused the mass killing of unbelievers and/or opponents, and in Eighteen-oh-something the Wahhabis massacred the city of Karbala (Qa'arba'ala?) killing 2,000 ordinary civilian citizens.
Wahhabis formed the main opposition to the (Islamic) Ottoman Empire, and all those Johnnies dashing around with TE Lawrence (you've seen the movie) were Wahhabis.
I'm led to believe that most Islamic terrorism has been committed by Wahhabis, who may have a more relaxed attitude to killing innocent civilians than do mainstream Moslems (to whom it is a sin) and who may not embrace the Prophet's teachings on the validity of other 'Abrahamic' religions (Judao-Christian), and who may also not regard suicide as a sin.
Interestingly, its critics believe that Wahhabis are the 'trouble from the Nejd' prophesied by Mohammed himself, as being a likely source of confusion and corruption of true Islam!
Worryingly, a huge number of Mosques (especially in the US and other Western nations) are coming under the control of Wahhabi Imams......