Saudi Arabia has been under attack by

Saudi Arabia has been under attack by
ISIS.[1]http://www.mepc.org/.../islamic-state-claims-mosque...
Here in the West we often see Islam as some kind of united
thing, but far from it.

The form of Islam predominant in Saudi Arabia is Wahhabism

It was started by
[2]https://en.wikipedia.org/wiki/Muhammad_ibn_Abd_al-Wahhab
at the same time the Revolutionary War was going on in the USA
for independence.,

Locke and Rousseau were a big hit in the Americas and France,
and the French Revolution was soon to follow, a generation
later.

In short, it was a time of worldwide upheaval in belief systems.

[3]https://en.wikipedia.org/wiki/Methodism formed around the
same time, a movement that was breaking away from the Anglican
church; and in distinction from other "Back to Basics"
movements, it was not "Bible Only" like some groups, or "God
Predestined" like Calvinism and its offshoots, but rather faith
/ good conscience as the pure core.

Anyway, all that aside, around the world people were unhappy
with the messy way things were and wanted to cut away to some
form of "basics", strip away culture as it was, rebuild culture
in a more pure image; each trying to create their Utopias.

Wahhabism is a modern (post 1750s) religious movement and has
similar Evangelical tendencies as some segments of Christiandom
have, and as some movements within Scientism and New Atheism
have today.

References

Visible links
1. http://www.mepc.org/articles-commentary/commentary/islamic-state-claims-mosque-bombing-saudi-arabia
2. https://en.wikipedia.org/wiki/Muhammad_ibn_Abd_al-Wahhab
3. https://en.wikipedia.org/wiki/Methodism