ideology and behavior considered as extreme in a pejorative sense

Political views and ideas which are far from the mainstream are called extremist. Such views often violate common moral standards. As an example, a group that wants to replace a democratic form of government with a totalitarian one is almost always considered extremist. Political or religious fundamentalism as well as fanaticism can also be seen as extremist.

Demonstration against democracy on the Maldives: the people demostrating want to introduce Sharia (Islamic law)

What is seen as extremist varies by country. People who support that Muslim women should wear a burqa may be seen as extremist in France, but such an opinion may not be extremist in Afghanistan or Saudi Arabia.