Perhaps my only quibble would be how the word radical was being used in an otherwise brilliant cartoon from the October 27 2012 cartoon by KAL in The Economist. I know the connotation can be made negative with “far reaching”. Islamic fascism (which includes theocracy even if the state co opts religion) would be more accurate.
I know that some people want to draw a distinction between Islam and those that really believe in a violent Jihad against anything they class as anti-Islam. The secularist principle allows harmony of religion and individual liberty, providing people accept the idea of pluralism. Not forcing others to conform to your religion.
So maybe we should say Islamic extremist as in the TV special by West Wing: