Gregory Dunn has a fine essay on Bush’s speech, he calls it "God and Empire: Some Theological Reflections." The last paragraph is worth quoting by way of encouraging you to read the whole thing:

"The most remarkable moment of Bush’s
speech is his closing: not "God bless America," as he often
says, but the more explicit "May he guide us now, and may
God continue to bless the United States of America." This
should not be missed: he closes with a prayer. As we strive
to be just, we need guidance, so we humbly ask God for it.
And we remember that the phrase "God bless America" is
not a statement or a command but a supplication. Liberty
may be our right, but divine favor is not. So we humbly ask
for it. Our situation is precarious. (It always is.) So we
pray."