There is a saying in Hindi - 'अपनी गली में कुत्ता भी शेर बन जाता है.' Literally translated, 'In his own backyard, even a dog becomes a lion'. The same is true for most humans too. I think the leading cause of intolerance in this world is the lack of ability to see the perspective of the other side. No matter how much you read, know or see the other side's perspective via books,TV or some other form of media, unless you experience it yourself, you will never understand it completely.
Everyone likes to be in the comfort of their own backyard. There is something relaxing about knowing where things are and what to expect. But if you truly want to know about yourself and the other side, you have to put yourself in completely unfamiliar situations. Easy to say and hard to do is what most of us would think. But one of the most obvious ways to do this would be travel. It may sound far-fetched, but if Osama Bin Laden had travelled and lived in western countries instead of just being in his comfort zone of Islamic countries, he probably would not have done what he is doing now. If only George Bush had travelled more of the middle-east, he probably would know the difference between Sunni and Shia and may not given the orders for invading Iraq.
Human nature is such that you are most likely to be obnoxious to others in your own backyard than in somebody else's. Everyone is capable of it and everyone has their own version of a backyard. Stepping out of this comfort zone could be the only way to reduce animosity to your fellow beings. Until we do that, the idea of showing someone else down to feel better will seem much more easier than just simply elevating yourself.