Christian Nationalists are vocal in their advocacy of America becoming a Christian state. This may lead some to conclude that Christianity is the only basis for their ideology, but this would be a mistake. Christian Nationalism is at least as nationalistic as it is Christian and this nationalism on behalf of America is important in their policies, attitudes, and values. Whereas patriotism may simply be a positive attitude towards one's country, nationalism tends to be much more extreme in that it sees the nation as exceptional, something to be placed above all else. This helps justify policies in which traditional standards of morality or justice are abandoned. When it comes to defending the nation, everything is permitted.
If Christian Nationalists were merely Christian, we might expect them to make common cause with Christians around the world -- Christianity is, after all, a universal religion. Anyone can become a Christian and all Christians are equal before God. Not everyone is an American, however, and not all nations are equal in the eyes of Christian Nationalism. Christian Nationalists frequently adopt positions at odds which Christians elsewhere in the world because those policies are designed to advance American economic, political, or military interests. Christian Nationalists also frequently adopt positions which are arguably at odds with traditional Christian moral values, but this is also because those positions advance nationalistic interests.
All of this is evident in America's War on Terror. Christians elsewhere in the world, including conservative evangelicals, object to America's invasion of Iraq and as well as America's treatment of detainees. Christian Nationalists, however, don't even try to defend their positions via Christian traditions or doctrines. America's actions in the War on Terror are justified in almost Machiavellian terms in which the survival of the nation is all that matters. The actual suffering of detainees or Iraqis is less important than the theoretical suffering of Americans in the future if harsh tactics aren't adopted. The immorality visited upon detainees and the injustice of the loss of domestic civil liberties are less important than the immorality and injustice of a theoretical terrorist attack in the future if detainees aren't vigorously questioned (i.e., torture).
This image is based on a World War I poster encouraging Americans to invest in the Liberty Loan (war bonds).