Fundamentalisms

What is it that makes fundamentalisms of all sorts so dangerous?
Simple and sincere beliefs ought not lead to physical, emotional or spiritual violence.
I find myself thinking of old and new adages:
Can't we disagree without being disagreeable?
And can't we all get along?

There is something imperial about dangerous fundamentalisms:
the desire to reshape the world in one particular image without consent or cooperation;
the assumption that one individual or community knows what is Right, True and Good;
a classist superiority complex that obligates Those-Who-Believe to convert those who do not believe as/what the True Believers believe; the conviction that God in on one side and not the other;
the presumption that God needs the help of the True Believers;
the view that God/good is narrowly defined.

These beliefs are not simple, however sincere they may be.
Fundamentalisms are comforting in a dangerous, inconsistent world.
Complicated, nuanced faith and belief are not simply comforting.

Is false certainty better than no certainty at all?
For millions, perhaps billions, the answer is clearly, yes.

I like to think that education and amelioration of desperate circumstances will reduce the appeal of and perceived need for fudamentalisms. But is there something to be learned from fundamentalisms?
People clearly need certainty.
How can we who teach, preach, pastor and profess offer the satisfaction and comfort that certainty brings while maintaining our simple and sincere faith in the complex and complicated?