Is it appropriate to say that some denominations are more "extreme" than others? I've been thinking about the actions of people under the guise of religions. It is clear to me that there are extremists in any religion, under any denomination, just as there are more liberal people. My question is whether it is appropriate to categorize certain religious denominations as "extreme" intrinsically, as opposed to merely the followers being extreme. 

Are only people "extreme"? Or are there aspects of certain denominations that foster extremism in their followers by the nature of the views they preach?

If religious denominations can be weighed by differing amounts of extremism, are there any resources which list each denomination in order of "magnitudes of extremism"? Stated differently, if you agree that there are differences in "extremeness" among religious denominations, you must also (logically) agree that some are more extreme than others, and thus ultimately believe in one that is not extreme; i.e. the "true" base religious standpoint (whether it exists as a denomination today is irrelevant, you have to believe such a standpoint exists if you hold such a position).

Has there been any writing by Christian believers on this subject?
I'm going to take a risk with an initial assumption:  Since it's hard to find non-hostile documentation referring to specific denominations as "extreme" or "extremists, I'm going to offer the next best thing:  Denominations that are widely accepted as Fundamentalists.  

The assumption is that by "extreme" you mean "fiercely attached to a core set of beliefs, and less likely to compromise on those positions." This somewhat fits, because of your comparison with "more liberal" people, and Fundamentalism emerged as a counter-force to liberal movements within the Church.

I do realize that there are other ways the term "Extreme" could be interpreted.  It could mean "dangerous" as in those that would kill to defend their beliefs, or the ones that would hole up on a compound somewhere, arming themselves against the invasion of Satan's armies.  My answer doesn't address that type of "extreme".  I'm shooting for what I THINK you're looking for.  Forgive me if I'm wrong.

Fundamentalist Christians are defined as such:


  Fundamentalist Christianity, also known as Christian Fundamentalism or
  Fundamentalist Evangelicalism, is a movement that arose mainly within
  British and American Protestantism in the late 19th and early 20th
  centuries among conservative evangelical Christians, who, in a
  reaction to modernism, actively affirmed a fundamental set of
  Christian beliefs: the inerrancy of the Bible, Sola Scriptura, the
  virgin birth of Christ, the doctrine of substitutionary atonement, the
  bodily resurrection of Jesus, and the imminent personal return of
  Jesus Christ.


Various sources can be found that compare Fundamentalists with Mainline Christianity, and Pentecostals.  Of course, all of these are relative terms, but I think the closes you can get to the list you're asking for - a list of denominations that are more extreme would be to look at a list of denominations that are accepted as Fundamentalist.

There are such lists on the Internet, but (oddly enough) the best I found was at Wikipedia.

http://en.wikipedia.org/wiki/Category:Fundamentalist_denominations

My denomination is listed there, and I'd agree - I fit that definition of Fundamentalist, as to my fellow Church members.  However, nobody in my church (by that, I mean my local West Salem Baptist Church, not Baptists as a whole) would dream of using our devotion to the "old fashioned" positions as an excuse for hostility toward others, as hinted at in the question you linked to.  We take the commandment to love our enemies as seriously as we do the Trinity, or any of the other beliefs that define Fundamentalists.

Other than that, the Handbook of Denominations in the United States gives information similar to what you're looking for - the core beliefs and tenets of each denomination, but not with a chart or ranking in order of Fundamentalism.  You can look at each denomination on your own and use your own definition of Extremism to determine which you think are extreme.