...United States flag? Of course not.
Unlike the European flags, a large number of which do have crosses, the American Founding Fathers knew this had to be a secular nation or they would risk all the same persecutions they just escaped. They would never have stood for a religious flag because...
...popular with the voters? Jeb Bush goes from Episcopalian to Catholic because he's in Florida.
George W. Bush goes from Episcopalian to Methodist because he's in Texas.
John McCain goes from Episcopalian to Baptist because he was trying to woo Southern voters.
And now Newt Gingrich goes...
Look at all the arrogance, savagery, xenophobia, selfishness, bigotry and ignorance that goes with your religion.
That's not a Supreme Being; that's humans showing how pathetic they are at explaining the unknown.