Stanley Hauerwas argues that America is a nation of war (see, for example, War and the American Difference; Martin Marty makes the same point earlier in Pilgrims in their Own Land). Since America, with its various colonies reflecting the diversity of Tudor England, has always been a place of diversity, there has been little to hold us together as nation except for a shared geography. We have no common religion, except for Protestantism. Yet Protestants have been and still are quite different within the various denominations, and other religions such as Catholics and Jews had a clear presence in colonial America. America was a blank slate back then, and religious change and innovation prospered quite freely since there was no established authority to prevent you from founding utopian places or religious sects (think the Oneida community or the Shakers). What did hold us together as a nation were a few key elements: a civil religion that promoted America itself as an object of worship, a common Protestant culture as differentiated from non-Protestant religions such as Catholicism, a belief in the unity of religious and political freedom, and war.
War in America is odd in many ways, as we have had few wars on our own soil. Nor have there been sustained religious wars here, although the battles with Native Americans and the Utah War might count. Yet wars and patriotism have been an important part of American history: War of Independence, the Civil War, the World Wars, Vietnam, Iraq War, and the war on terror are all examples of times when America has renewed its dedication to itself and united its citizenry through war. With Lincoln and the Civil War, the idea that America was worth preserving and dying for, whatever the cost, was particularly enshrined.
It is the power of war in America that Hauerwas, as a Christian pacifist, particularly opposes. He argues that it has imaginary power over us, it is a kind of liturgy. By being ever thankful for the sacrifices of soldiers for our freedoms we offer up thanks to War while receiving our identity and belonging: we Americans are people who are free and love America. "Americans are a people born of war, and only war can sustain the belief that they are a people set apart. War is necessary to sustain their belief that they are worthy of the sacrifices of past wars," Hauerwas notes.
What can be added to Hauerwas' analysis, I think, is the place of revivalism in American religion. In many ways, American religion IS revivalism, and a strong element in American Christian revivalism is being ever grateful for Christ's sacrifice for us; our gratitude is never enough to repay the sacrifice Jesus made for us. It is this note of gratitude for sacrifice that powerfully connects with America's liturgy of war. It is here that we find that American mixture of the cross and the soldier (see here and here. Religious and political freedom are deeply connected in sacrifice; the sacrifice of Christ frees from hell and sin, and the sacrifice of soldiers frees us from tyranny.
There are many questions here. If gratitude is mandated by culture and political identity, is it true gratitude anymore? Does an overwhelming sacrifice such as Christ's not demand a never ending sense of guilt (one of Nietzsche's critiques of Christianity)? Hauerwas offers an important way of repair, I think. He echoes the voices of Girard and Hart (and, mostly importantly, Hebrews) by arguing that Christ's sacrifice ends all other sacrifices. Instead of enabling sacrifice and violence, Christ upends it. Christ's sacrifice means no more sacrifices through violence. Sacrifice should be given without violence or coercion and freely, gratefully accepted.