Of all the extremists, the worst are the moderates.  Moderate ideology is contradictory, irrational and just plain wrong.  Ideas should not be judged on the basis of whether they are "extremist" or "moderate" but on the evidence and arguments used to support them.  There is no reason to believe "middle of the road" positions are inherently better than "extremist" ones.  In some cases the "extremist" position is vastly superior to the "moderate" one.

The usual argument in favor of the "moderate" position is to take a situation, argue that moderation is best in that situation and then pretend that this applies universally to all situations.  For example, one old argument is the bravery argument.  Supposedly, you don't want to be too brave because that would lead to you getting into dangerous situations where you could get yourself hurt.  A little fear can be a good thing since it can help you avoid hurting yourself.  On the other hand, you don't want to go too far in the other direction.  A complete lack of bravery would lead to cowardice and running away when it would be a good idea not to, even from  things that couldn't possibly hurt you.  Thus, moderation is supposedly a good idea.  This may be true in the case of bravery, but it is a non-sequitur to apply this universally.  The moderate's logic implies support for slavery.  The "middle of the road" position on slavery would be to have a moderate amount of slavery - not too much and not too little.  The "extremist" positions would be to either have lots of slavery or no slavery at all.  On this issue an "extremist" position is undoubtedly correct - we should have no slavery at all.  Slavery is immoral; its abolition was a good thing despite what the moderates claimed.

Not everything should be in moderation.  We should not have rape in moderation.  We should not have genocide in moderation.  We should not have slavery or concentration camps or war crimes or sexism or racism in moderation.  These things should be completely abolished; to have them in moderation - as the "middle of the road" position would have it - is unethical.

Moderates are actually extremists, and far worse than many of the "extremists" they denounce.  The idea that one should ALWAYS take the "middle of the road" position on ALL issues is itself quite extreme.  One could alternatively always take the extremist position, which would be the opposite form of extremism as the moderate.  The middle position would be to sometimes take a "middle of the road" position and sometimes take an "extremist" position.  By demanding a "middle of the road" position on everything the "moderate" is actually practicing a form of extremism.  Moderate ideology is thus is self-refuting.  If everything should be practiced in moderation than moderation should also be practiced in moderation.  If moderation is practiced in moderation than you are not practicing everything in moderation - a self-contradictory circle.

A further problem with moderate ideology is that with the proper manipulation of the political spectrum one can make almost any political position the moderate one.  For example, define one end of the spectrum as being Democratic Socialism and the other being Anarchism.  The "middle of the road" position in this spectrum would be Marxist-Leninism.  This manipulation of the spectrum is implicit in "moderate ideology."  For example, most contemporary moderates would denounce the belief that we should have a moderate amount of slavery as “extremist,” even though it was the position defended by moderates prior to the outlawing of slavery and is logically the middle of the road position.  Most contemporary moderates position themselves between (left-)liberals and (neo)conservatives, which are viewed as the extremes.  But a few centuries ago most of the things advocated by both liberals and conservatives would have been viewed as extreme leftist.  The spectrum has shifted, most people today are somewhere on the liberal-conservative spectrum - there is almost no one advocating absolute monarchy or feudalism anymore.  The positioning of the moderate between liberals and conservatives is arbitrary; they could just as easily position themselves between constitutional monarchists and absolute monarchists, which would be a position far to the right of most conservatives.  In practice the moderate believes whatever happens to be the mainstream position(s) of the time.  They simply sum the dominant philosophies together.  Rational analysis is thrown aside and instead whatever is most popular is believed regardless of how wrong it may be.  Anyone who does not go with the most popular ideas is denounced as "extremist."  "Extremist" is essentially a derogatory term for any idea that is unpopular.  Someone who believes in a moderate amount of slavery would be labeled an "extremist" even though his or her position is technically moderate because that idea is extremely unpopular in contemporary society.

Most moderates rely as much on stereotypes and anti-"extremist" prejudice as on rational arguments.  This is not surprising, since their arguments in favor of "moderate" ideology are usually very weak.  One common stereotype is that of the "violent extremist" who uses atrocities and terror to impose his/her way.  While there have been "extremists" (people with unpopular views) who have used force, this stereotype is simply wrong.  There are also "extremists" who are (theoretically) opposed to all use of violence under all circumstances.  They are called pacifists.  Moderates, on the other hand, have historically used extreme amounts of violence.  Moderates have supported wars, terrorism and other uses of force when it was the "middle of the road" position.  The "middle of the road" position moderates claim to advocate implies support for a moderate amount of violence, war, terrorism and atrocities.  Moderates support the state, the most violent organization in human history.  They are thus far more violent than two forms of "extremism" - (true) pacifism and anarchism.  How "extremist" (popular or unpopular) a position is has little to do with how violent its' adherents are.

Probably the most common stereotype is that of the "dogmatic extremist" who only reads and views things that agree with his/her position and either avoids or automatically rejects anything which does not agree with that position regardless of the merits of their argument.  This is simply false; although there are individual "extremists" who are dogmatic it is not true of "extremists" as a whole.  In fact, "extremists" are generally less dogmatic than "moderates."  Dogmatic people are unlikely to change their views on anything, but almost all "extremists" start out believing a more mainstream ideology and later change to a different philosophy.  You are far more likely to find dogmatic people among mainstream ideologies than "extremists" because dogmatic people will not change their philosophy and thus stay with the more popular mainstream ideologies.  Moderate ideology is inherently dogmatic.  Moderates automatically reject any idea that is not moderate and label it "extremist" SOLELY because it is not moderate, regardless of the merits of the argument.  That is the definition of dogmatism.  To reject an idea not on the basis of its merits (or lack thereof) but simply because it is not moderate is the height of dogmatism.  When the moderate says "extremist" s/he means "heretic."

The validity of a philosophy has no automatic relationship to how "extremist" it is.  Whether it is "middle of the road" or "extremist" is irrelevant, ideas should be judged on the basis of their merits NOT how "extremist" they are.  Moderate ideology in practice amounts to a blind defense of the status quo and denouncing all dissent as "extremist."  Such an ideology is more appropriate for a Borg drone than a thinking person.