More from the Wallis article cited below

Christians should always live uneasily with empire, which constantly threatens to become idolatrous and substitute secular purposes for God’s.
The sad thing is, most American Christians seem all too willing to defend the actions of America, and many take greart pains to “baptize” the strategy with God’s blessing. This is why “God Bless america” becomes such a painful phrase to me now. Very rarely anymore does that mean anythng other than “All Christians must see it as Bush and the White House sees it”, leaving those who pray for the wisdom of God to say instead “God speak to America” in leiu of “God BLESS” America, although theologically, they should be the same thing. I could never put a bumper sticker on my car like that, unless more Christians learn that God’s blessing does not align with whatever empire is invoking the name.