When a nation fights for its life, ideology goes by the board.

Gen. Washington danced a jig when he heard King Louis XVI had become a fighting ally in our Revolutionary War against the Mother of Parliaments.

In our Civil War, Abraham Lincoln made himself a dictator, closing newspapers, suspending habeas corpus, and locking up editors and legislators.

Woodrow Wilson went to war to “to make the world safe for democracy” alongside five of the most rapacious empires on earth: the British, French, Russian, Italian and Japanese.

During World War II, our ally that did most of the fighting and dying was the Soviet Union of Joseph Stalin.

During the Cold War, America welcomed as allies Chiang Kai-shek, Salazar, Franco, Diem, Somoza, the Shah, Suharto, Syngman Rhee, Korean generals, Greek colonels, militarists in Brazil, Argentina, Turkey and Pakistan, and Marcos and Pinochet.

But with the end of the Cold War and the coming of George W. Bush, America set aside a national interest-based foreign policy for a policy rooted in ideology, political religion. Not until the world is democratic, said Bush, can America be secure. We must “end tyranny in our world.”

“The requirements of freedom apply fully to the entire Islamic world,” said Bush in 2002. At the National Endowment for Democracy, he listed the “essential principles common to every successful society, in every culture.”

“Successful societies limit the power of the state and the power of the military — so that governments respond to the will of the people, and not the will of an elite.”

Comes now the acid test of democratist ideology.

Hosni Mubarak has been a loyal ally. He kept the peace with Israel and helped keep weapons out of Gaza. He fought beside us in Desert Storm and stands with us in the War on Terror. But he is also an autocrat who rules a regime where state and army are virtually one and where the opposition is squelched, when it is not imprisoned.

If a democratic Egypt is America’s goal, we will push for the removal of Mubarak, for the army to go back to the barracks, and for parliamentary and presidential elections where all parties participate.

But before we do this, we should be on notice what a democratic Egypt, where the government reflects the will of the people, may look like. According to the most recent Pew Research Center poll:

— Twice as many Egyptians identify themselves as Muslim fundamentalists as identify themselves as “modernizers.”

— By 95 to 2, Egyptians believe Islam should play a large role in Egyptian politics.

— While 48 percent of Egyptians say suicide bombings are never justified, 32 percent say “rarely,” 12 percent say “sometimes,” and 8 percent say suicide bombings are “often” justified. Half the people of Egypt believe there are times a suicide bomb is the right answer.

— Half of all Egyptians have a favorable view of Hamas, and one in five has a favorable view of al-Qaida.

— Three in four Egyptians believe cutting off the hand of a thief is proper punishment. Four in five favor stoning adulterers to death. And 84 percent favor executing Muslim converts to Christianity.

— Eighty-two percent of Egyptians regard the United States unfavorably, and 48 percent rate America “very unfavorably.”

— In a Zogby poll in 2010, 90 percent of Egyptians named the United States and Israel as threats, 86 percent said Iran had a right to pursue nuclear weapons, and 77 percent thought it would be a good thing if Tehran got the bomb.

Thus, if free and fair elections are held and the new government of Egypt, in Bush’s words, responds “to the will of the people, and not the will of an elite,” Egypt will become more Islamic, more hostile to us and Israel, and more supportive of Iran.

If that is a likely result of free and fair elections in Egypt, why does the U.S. government favor free and fair elections in Egypt? And if democracy in the Middle East could get us kicked out of the Middle East, why do U.S. policy-makers favor democracy in the Middle East?

Does the U.S. government believe what it professes to believe?

Would we support a “million man march” in Riyadh, as President Obama did in Cairo? Will we call for elections in Bahrain, where a Sunni king rules a Shia-majority statelet and the U.S. Fifth Fleet is anchored?

Not one of our Arab allies is a democracy. Should they all, as Mubarak has been told by Obama to do, prepare for a “transition”?

Across the Middle East in the last decade, we lost 6,000 soldiers and spent hundreds of billions of dollars. Yet we have never been more disliked, more reviled, more hated in that part of the world.

If the advancement of our democratic ideals imperils what the U.S. government says are our vital interests, is there not something fundamentally wrong with our Middle East policy?

Why keep borrowing untold billions from China, putting America’s children eternally in debt, to pursue a policy in the Arab world that has made this once-admired nation thoroughly detested across the Arab world?