and justice for all
Did God ordain our Union of States? Does God endorse the manner in which we, as a nation, occupy the earth? If Americans have the right to believe otherwise, then it is hypocritical to pledge allegience to "one nation under God" at the same time that you pledge allegience to "liberty and justice for all."
Frankly, I think the whole thing is problematic propaganda. True allegience to God would, in my view, disqualify you from most of what the Pledge promises. Only if your national affiliation trumps your other affiliations could the pledge to the US flag be made sincerely.
Incedentally, here are Dwight Eisenhower's words on accepting the 1954 addition of the words "under God" which have recently been found unconstitutional by the 9th Circuit Court of Appeals:
"In this way we are reaffirming the transcendence of religious faith in America's heritage and future; in this way we shall constantly strengthen those spiritual weapons which forever will be our country's most powerful resource in peace and war."
-from Hall of Heroes
Also, Thomas Oliphant of the Boston Globe has a good story on the history of the pledge and its author (Thanks to Travis for the link)