Am. Gov. #6

An interesting thing about early American history is that there was a strong attitude of "It's obvious that I, and my people, should have liberty," but then a strong denial of liberty to others who were different. As people of all religions, blacks, and women have gained more and more equality, it has seemed more and more obvious that this is how it should be.
It seems like a lot of the time, if not every time, people engaged in war (from armed conflicts to mere disagreements) will spend a lot of time finding differences between themselves and the enemy. The crusades, the Catholic-Protestant conflicts, even the current war in Iraq all involve people throwing out names and looking for way to be better than others.
What is it in people that makes them look for differences in others and hate them for it? Why do we not see others as they really are: people? Why would people fight for liberty for themselves and then turn around and deny it to others?
I think that if people would be able to stop looking for differences (in religion, in clothing, in culture, etc.) then conflict would happen less, and greater liberty would ensue. There would be more trust, less wars, greater happiness, less fear.
I guess the real question is: how do we, as a country and as a world, arrive at this state of mind? And how can we be an example to others of trust and reconciliation?