Some of it is a delusion where people see everyone else as monsters, was part of langoliers story. The idea that the masses of people are evil.
Has ideas of the living taking anything they want, the store they held out in, and the idea of snipping people in the head from a distance, PR or other stuff. Also the idea that the zombies are not coordinated and only act from impulse not thinking.
Then there is the other side, if you remove the violence, that the zombies are spreading love, and it is only seen as trying to kill someone by them being on the opposite side.
The side that shoots a friend if bitten, not feeling. Shaun of the dead did the best on that, just before anyone turned they spoke of compassion and love.
The zombie metaphor can be seen two ways, loving feeling people turning machines into feeling people. Or it can be seen as dumb uncoordinated people that don't think being an enemy to the self proclaimed living.
Same two sides and two views that are in everything else.
Shaun Of The Dead
http://www.youtube.com/watch?v=yfDUv3ZjH2kNote the coordination. Please pay attention :)