The real difference between the United States and virtually all other countries is that the United States has been unusually secure for much of its history, and very powerful for six decades or more. Realist theory tells you that when a state is really powerful, it will be less constrained by the power of others and it will be able to indulge all sorts of foreign policy whims. It can decide that it has "vital" interests on every continent; it can declare itself to be "indispensable" to almost every important issue, and it can convince itself that it really knows what is good for everyone else in the world. If you're wrong, it may not matter that much in the short term. If you are really powerful, in short, you can do a lot of stupid things for a long time.
I've been thinking about this a lot lately (yes, I have nothing better to do). It's still vexing to see how Obama's clear adherence to American exceptionalism is simply obliterated by the far right and the neocons. Why? I think it's because he's a Christian and not a Christianist. Christianism is essentially political, not spiritual. And for Christianists, America was founded by God and for God's purposes. The Providence that even atheists might appreciate in terms of America's role in world history is translated into divine exceptionalism for this one country. America is not exceptional because of the ideas in its founding documents - but because those ideas were divinely imparted.
In a way, that's why traditional Christianity is so bad a vehicle for Christianism. Jesus' message is far too subversive for a truly conservative, capitalist, pro-torture, pro-war movement.
The idea that there could be a "chosen people" for the Christian God is, also, absurd. Paul, while acknowledging the Jewish roots of Christianity, clearly stated that no nation or nationality or identity could exclusively exemplify the words of Jesus. Neither Jew nor Gentile, neither male nor female, remember? How could such a God favor ... the United States in 20th and 21st century history?
That's why, it seems to me, that Mormonism is much more coherent a faith platform for the rightist religious popular front that the GOP increasingly is. Because it places Jesus in America and gives America a unique role in global salvation. Christianity - the actual religion, not its strip-mall bourgeois impostor - is universalist, not nationalist. What the far right means by American exceptionalism is a divinely blessed and guided country, whose enemies are God's enemies, whose role in the bringing about of the End-Times is unique, and who therefore cannot truly do wrong. That's how Christianists like George W. Bush can say "damn right!" when asked if he would authorize torture again. Merely because he is the American president, he cannot definitionally commit an absolute evil - placing him on the same moral plane as, say, the Communist Chinese whose torture techniques he cribbed.
So we can engage the exceptionalists rationally and still fail to reach them or understand them, because we are missing the point. The point is the hubris and self-righteousness that a certainty of divine blessing gives you. And when you get to declare yourself beyond good and evil, you truly are exceptional - and can torture knowing that it is all part of God's will in God's holy war.
And this is what Christians of a more traditional type would call the work of the devil.