There is one main reason I am a pacifist: civilians should never be punished for a war perpetuated by their country's leaders.
From Al Jazeera: "A recent study carried out by a UK polling firm says that more than a million Iraqi civilians have been killed due to violence since the US invasion of Iraq in 2003." Although there's a lot of debate about the exact number (the Iraqi government and others have claimed that the number was much lower) people need to see through the story of numbers and realize that even one civilian death is far too many. This "war on terror" is producing terrifying lives for the non-militant people of Iraq. I for one cannot imagine what is would be like to live in fear that you might end up in the wrong place at the wrong time and be added to the striking number of other dead civilians.