What is it Really?

Just in the past week we've seen Islamic extremism described as a mental illness or a far right ideology.

Well, which is it? Who defines these descriptions?

Because I know what it is and it is neither of those. 

I assume it's a mental illness when a Christian converts? After all, how could someone convert from the kind, caring Christian faith to Islamic extremism?

Or maybe it's a far right ideology because it aligns with those Germans from the Thirties that hated Jews?

I do love the mental gymnastics the Media and the Elites use to describe the extremist death cult that is Islam.