The rebellion is in the lust for power, money, and/or pure hatred. God does not intend for us to be consumed by those things. This doesn't apply just to war, but life in general. When war is waged for those reasons, it is sin. I wouldn't say we are "petulant", but rebellious is more accurate. I'm speaking on a global scale, not just wars that the U.S. has waged.

Sometimes war is justified, as it was after 9/11. But in general, wars are fought for the wrong reasons.