Here's some good advice from novelist John Brunner, from his novel The Traveler In Black:
"But -- but I counseled against this foolishness!" stammered Jacques."No," corrected the one in black. "You did not counsel. You said: you are pig-headed fools not to see that I am absolutely, unalterably right while everybody else is wrong. And when they would not listen to such dogmatic bragging -- as who would? -- you washed your hands of them and wished them a dreadful doom."
"Did I wish them any worse than they deserved?" Jacques was trying to keep up a front of bravado, but a whine had crept into his voice and he had to link his fingers to keep his hands from shaking.
"Discuss the matter with those who are coming to find you," proposed the traveler sardonically. "Their conviction is different from yours. They hold that by making people disgusted with the views you subscribed to, you prevented rational thought from regaining its mastery of Ys. Where you should have reasoned, you flung insults; where you should have argued soberly and with purpose, you castigated honest men with doubts, calling them purblind idiots. This is what they say. Whether your belief or theirs constitutes the truth, I leave for you and them to riddle out."
I first read this many hears ago when in high school or junior high and I still remember it. While I have fallen into the trap of flinging insults where I should have reasoned too many times, I do try to be a moderate extremist and use reason as much as my worse nature permits.
Now you have encouraged me to go out and re-read the "Compleat Traveller in Black" (I guess the version we read in high school was missing a story).
I hear we didn't miss much.