The Word That Ends In Ism

What is it in the word that ends in ism that it can cause mistrust between people to grow
At times it does heat up strong feelings that's all of it I can claim to know
It never brings people together only seems for to drive them apart
Though red is the blood in all of us that pumps up the valves of the heart
A word that gives rise to offensive insults and because of it flags are unfurled
And a word that in part is responsible for a very disturbed Human World
It never brings people together it always does seem to divide
It offends those we look on as different and it gives rise to wars Worldwide
It does have parades in it's honor but it also does deeply offend
It can make you many an enemy and of one like minded make you a friend
It does not make for better human relations of that why otherwise pretend
The word that has so many meanings but that always in ism does end
If you do not know what I am on about then here is some advice from me
For more information on it do refer to your dictionary.