A Reuters article contains the intriguing phrase, intriguing because reportedly it's from the Taliban: "Muslims also should avoid extremism in religion".
Jihad Watch remarks:
The Taliban, in saying this, demonstrate that they don’t consider themselves to be “extremist.” This word is thrown around everywhere, but like “moderate,” no one bothers to define it precisely. Everyone assumes that its meaning is obvious, but it isn’t. It would be useful and illuminating to have a debate between Muslims who support the Taliban and Muslims who oppose it on what constitutes “extremism.” But that will never happen, as it would require honest discussion of Islamic doctrines that Muslim spokesmen in the West are doing a fine job of obfuscating.It's true: nobody has defined "moderate" or "extremist" in Islam. That's how and why these terms are used to foster the Islamophilic agenda: because they're useless. The fact that the Taliban can use the term "extremism" to dissociate itself from it (and to condemn it), as they don't consider themselves extremist, tells you a lot about the vagueness and consequent inutility of the word.