It seems to me that the people who get the most upset at opposing viewpoints, are the ones who aren’t fully confident in their own. Why else would they feel so threatened? Why else would they feel so manic about enforcing their point of view, if they weren’t fully confident that it was a solid, obvious opinion? Perhaps they also fear that they’ll be steamrolled by the opposing opinion if it’s allowed to exist, given that they’re already so insecure about their own.
As with everything, the solution lies in less outward focus, and more introspection. Rather than worrying so much about what they are thinking and doing, the way to true peace is by mindfully going within.