In a perfect world, maybe the bond between nation and citizen are weak or nonexistent. Unfortunately, this isn't a perfect world.
Nations owe their existence to violence, rising from the common need for defense. Well, it looks like things haven't changed all that much in the last 5000 years. Your nation provides for your protection (even when the threat is internal, and I sincerely hope you have been spared any pain). Taking advantage of the national infrastructure obliges us to support it. Likewise (especially in democratic systems) citizens are responsible for their nation's policies and actions.
On the other hand, I consider myself a free man. Free to take many actions to protest and influence my government, as well as the governments of others. Killing is not one of those things. That is what this is about.