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Thank you.

I'm not really sure if this wholy answers your question but I can provide some information that will hopefully at least enlighten the issue a little.

As you probably know there are different types of Musilms. Shia Islam and Sunni Islam. Then there's different types of movements within Shia and Sunni Islam again. Different movements and ideologies interpret the Quran differently. Some say Sharia should be a vital part of any lawmaking, some say Sharia should be advised when deciding on laws and some say Sharia shouldn't matter for example.

One movement is Salafism. Ever seen a muslim with beard, but no moustache? That's a Salafist. One movement within Salafism is Wahhabism. Wahhabism comes from the 18th century theologian and scholar Muhammad Ibn 'Abd Al-Wahhab. Wahhabism can be described as an ultra-conservative and fundamentalist movement of Islam. Al Wahhab meant that the muslims of the time had strayed to far from the original Islam of the prophet and his followers. Wahhabism tries to go back to the roots of Islam and live like the Prophet would have. Wahhabism is by nature very violent and intolerant of other religions and islamic ideologies. From their point of view Wahhabism is the only true ideology and no matter if you are a muslim with a different ideologi like Shia Islam or if you are a Christian you are an infidel. It's very important in Wahhabism to differentiate between infidels and true believers. In this ideology there's no room for philosophical speculation of the Quran, instead it's to be taken literally. Thanks to it's violant nature it's very easy for Wahhabist countries to justify political expansion by use of violence and force.

Thanks to Al-Wahhab and his alliance with the Saud family, Wahhabism is today the official "ideology" of Saudi-Arabia. Together they declared Jihad on nearby Muslim tribes and counqered territory in what is today's Saudi-Arabia. In the mid 50's Saudia's economy skyrocketed thanks to oil revenues. Suddenly they went from being a very unimportant country on the world stage to being the worlds biggest supplier of oil. The money, and increased influence gave Saudia-Arabia the means to expand and spread it's ideology. They funded Mosques, Islamic Centers, and schools for Muslim Children where built in both Muslim and Non-Muslim countries with financing from Saudi-Arabia. Of course Wahhabism was the movement/ideology being thought at all these schools.

ISIS is one of the terrorist groups that bases itself on Wahhabist ideology. Since they are taught to consider everyone but themselves infidels it makes it rather easy for them to hate western countries, and justify their actions. Yes Saudi-Arabia may have joined forces against ISIS, but all of it's ideology and violent actions dates back to the 17th century, Al-Wahhab and Wahhabism.

Hope it helped. I apologize for any grammar mistakes.

Sources:

Roel Meijer: Global Salafism

Peter Mandaville: Islam and Politics 2nd Edition