This is the first in a series exploring the concept of American exceptionalism. On Monday, we examine areas in which other countries lead the way.

By Dan Gilgoff, CNN.com Religion Editor

(CNN) – It’s safe to say the first European arrivals to New England wouldn’t recognize today’s debate over whether America is exceptional.

Though the United States wouldn’t be born for another century and a half, the Puritans arriving in the early 1600s on the shores of what would become Massachusetts firmly believed they were on a mission from God.

In other words, they had the exceptional part down pat.

Fleeing what they saw as the earthly and corrupt Church of England, the Puritans fancied themselves the world’s last, best hope for purifying Christianity - and for saving the world.

The Puritans never used the word “exceptionalism.” But they came to see Boston as the new Jerusalem, a divinely ordained “city upon a hill,” a phrase Massachusetts Bay Colony founder John Winthrop used in a sermon at sea en route from England in 1630.

“They were reinterpreting themselves as God’s new Israel,” Boston University religion professor Stephen Prothero said. “They were essentially playing out the biblical story.”

To modern ears, that literal exceptionalist thinking could sound at once both exotic and quaint, which makes the idea’s staying power and influence throughout American history all the more remarkable.

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Nearly four centuries after Winthrop uttered the words “city on a hill,” President Barack Obama finds himself responding to charges from Republican challenger Mitt Romney that he has insufficient faith in American exceptionalism.

“Our president doesn’t have the same feelings about American exceptionalism that we do,” Romney said at a campaign stop this year. “You have an opportunity to vote and take the next step in bringing back that special nature of being American.”

Obama has pushed back on that claim, saying in a recent speech that “the character of our country … has always made us exceptional.”

Though the particulars surrounding the idea have changed, the bedrock belief that America is exceptional when measured against the arc of history and against all other nations has helped forge the nation’s defining moments, from the American Revolution and the country’s dramatic expansion west to the Civil War and both World Wars.

More recently, arguments about American exceptionalism have helped elect and unseat presidents – and have fed a debate about whether the phrase still has any meaning.

'An asylum for mankind'

For New England’s Puritans, exceptionalism was a religious idea with big political repercussions.

They thought the Protestant Reformation, which had been set into motion a century before, hadn’t gone nearly far enough in rooting out the corruption of the Roman Catholic Church.

Puritans saw the pomp and hierarchy of the Protestant Church of England as too much like another papacy.

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In New England, Winthrop and his fellow travelers established a theocracy that they hoped would be a model for English Christianity.

“They had to succeed to bring about this promised apocalyptic history that would culminate in the second coming of Christ, hopefully to New England,” said Deborah Madsen, an American studies professor at the University of Geneva.

“To fail would be to fail the world on this grand, transcendent scale,” said Madsen, who has studied the idea of American exceptionalism throughout U.S. history.

With the stakes thought to be so high, there was intense social pressure among Puritans to adhere to a strict moral code.

Everyone looked for signs that they were among the elect destined for heaven and kept a watchful eye out for neighbors who might be backsliding. The starkest example: the Salem witch trials of 1692, in which 19 people were hanged in Massachusetts for allegedly practicing witchcraft.

“If the members of the community fulfilled their part in the work of sacred history, not only would the individuals find salvation, but the whole community would be saved,” Madsen said, summarizing Puritan thinking. “But if any individual failed to live up to this grand destiny, the entire community would be denied salvation.”

Being God’s chosen people, it turned out, wasn’t all roses.

America exceptional? Not by the numbers

As new arrivals and subsequent generations enlarged colonial America, the Puritans’ faith-based ideas were gradually secularized.

By 1660, it had become clear to the Massachusetts theocrats that they wouldn’t be exporting their ideas abroad anytime soon. That was the year the British monarchy was restored after a decade of rule by the Cromwells, putting an end to Puritan rule in England and re-establishing the Church of England as a political power.

And with new Enlightenment ideas making their way from Europe about a rational universe knowable through reason, the Puritans’ quest for perfect religious institutions gave way to a colonial quest for perfect political institutions.

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The democratic ideas that made up this new political exceptionalism owed plenty to Winthrop & Co.

“Puritans had mapped out the relationship between church and the community that included the seed of democratic participation,” said Madsen. “The idea was that everyone had rights but also responsibilities.

“By fulfilling their responsibilities and respecting the rights of others, they would achieve happiness through the social contract.”

That egalitarianism helped lay the groundwork for the American Revolution, though Madsen notes that “the terms of reference had changed from salvation to democracy.”

America’s revolutionaries were keenly aware that their calls for democratic government in the face of English rule were exceptional for their time.

“Every spot of the old world is overrun with oppression,” Thomas Paine wrote in 1776 in “Common Sense,” which helped galvanize colonists toward the Revolutionary War.

“Freedom hath been hunted round the globe,” Paine wrote. “Asia, and Africa, have long expelled her. Europe regards her like a stranger. … O! receive the fugitive, and prepare in time an asylum for mankind.”

The Puritan vision of America as world’s godly beacon had been replaced by the image of the nation as the world’s workshop for political and social progress. America’s founders wanted to break with what they saw as the corruption of European politics and society, where a person’s status was mostly a matter of inheritance.

By contrast, the founders proposed in the Declaration of Independence “that all men are created equal, that they are endowed by their Creator with certain unalienable Rights.”

While other republics had come and gone, many of the founders who signed the Declaration - and, later, the Constitution - wanted the American Republic to endure forever.

This was city on a hill 2.0.

Manifest destiny

Reading the founders’ paeans to American exceptionalism - about aspiring to “secure the Blessings of Liberty to ourselves and our Posterity,” as the Constitution puts it - can put a lump in your throat.

But their vision excluded huge swaths of the population, like women and slaves. And other applications of the idea had their own dark sides.

Take Manifest Destiny.

As the nascent United States strove to expand westward in the 1800s, its leaders faced major problems, including how to justify taking land that belonged to Europe or that was occupied by Native Americans.

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Manifest Destiny – the idea that it was God’s will for the U.S. government to occupy North America or all of the Americas – offered a big part of the answer.

“A civilization that has the sanction of God is always the ultimate justification,” said the University of Geneva’s Madsen. “The idea was that God had made it manifest that the U.S. should expand. … It’s not much different than the idea of American exceptionalism.”

Like many facets of exceptionalism, the notion of Manifest Destiny wasn’t entirely new.

In the 1500s, Queen Elizabeth of England had established herself as a divinely ordained monarch whose reign had been presaged by the Bible. That mythology, which inspired Puritan exceptionalism, had helped English plantation owners justify forays into what is now Northern Ireland.

In the same way, Manifest Destiny helped justify the United States as it laid claim to European land and forcibly removed tens of thousands of American Indians. Many asserted that the campaign was meant to civilize or Christianize the natives, making good on America’s “chosenness.”

And the American image of a continent brimming with virgin land – which denied the presence of American Indians there – synched nicely with long-held exceptionalist visions of an unspoiled and utopian New World.

“Our manifest destiny (is) to overspread the continent allotted by Providence for the free development of our yearly multiplying millions,” American newspaper editor John S. O’Sullivan wrote in 1845, arguing for the annexation of Texas, in what is believed to be history’s first mention of Manifest Destiny.

It’s hard to know how much America’s leaders truly believed in the idea versus how much they employed it for purely political ends. Manifest Destiny certainly had high-profile critics, including Mark Twain, who declared himself an “anti-imperialist.”

“If you’re a cynical person and you see something like the Mexican-American War as a land grab, you can say this idea of Manifest Destiny was construed to create a moral tissue for a war of aggression,” Boston University international relations professor Andrew Bacevich said.

The westward expansion was driven largely by Southerners who wanted to farm the land and expand American slavery.

But abolitionists like Frederick Douglass also appropriated American exceptionalism, arguing that the nation’s “peculiar institution” was evidence that America was falling short of its Christian mandate.

That abolitionist line foreshadowed a key argument of 20th-century liberals: If America is exceptional, it’s because of the decisions we make around justice, not because of innate “chosenness.”

By Douglass’ time, American exceptionalism was so deeply entrenched in the American psyche that it transcended religion. Abraham Lincoln, often described as a deist - believing in a distant, uninvolved God - was nonetheless a hearty exceptionalist.

“He believed that America was leading the way in history toward democracy and equality,” said Dorothy Ross, a history professor emeritus at Johns Hopkins University. “At that time, Europe is still steeped in monarchs and failed revolutions, and America was still the only mass democracy in the Western world and believed that it was leading the historical way.”

Even the relatively unreligious Lincoln came to see the hand of God actively participating in American history through the Civil War.

“He gives to both North and South this terrible war,” Lincoln said in his second inaugural address, referring to God. “American slavery,” Lincoln said, was something that “He now wills to remove.”

The first president to say it

Despite its centuries-old influence, the term "American exceptionalism" didn’t emerge until sometime in the past 100 years.

Some historians say it’s unclear who coined the phrase, while others credit Joseph Stalin with doing so in 1929, when he admonished American communists for suggesting that the United States’ unique history could make it immune to Marxism.

In his reprimand, the Soviet leader decried “the heresy of American exceptionalism.”

Ironically, American intellectuals and eventually the broader public came to embrace the term, especially in the years following World War II, even after communists used the Great Depression as evidence of Stalin’s alleged "heresy.”

Just like President Woodrow Wilson had done in World War I, Franklin Roosevelt and Harry Truman justified American involvement in World War II largely on the basis that the country had been chosen to lead and transform the world.

After the Second World War, “the United States had emerged as the strongest country,” said Johns Hopkins’ Ross. “Social scientists began studying things like national character and what makes America unique.”

American affection for the idea grew during the Cold War, as the U.S. attempted to distinguish itself from the “godless” Soviet Union.

“Our governments, in every branch ... must be as a city upon a hill,” John F. Kennedy said in a Boston speech just before his inauguration in 1961, citing John Winthrop by name.

In the ’60s and ’70s, however, American scholars and others began challenging the idea of American exceptionalism, mostly from the left and especially after the Vietnam War, which liberals criticized as a costly exercise in American hubris.

Historians began to see exceptionalism as a scholarly construct, a way of interpreting American history rather than as accepted fact.

Ronald Reagan illustrated the partisan gap around the idea, speaking of America as a “city on a hill” and attacking President Jimmy Carter for allegedly showing weakness on the world stage, including in the Iran hostage crisis.

“We cannot escape our destiny, nor should we try to do so,” Reagan told the first annual Conservative Political Action Conference in 1974. “We are today the last best hope of man on Earth.”

President George W. Bush employed similar rhetoric in his global “freedom agenda,” even after initially pledging a “humble” foreign policy.

Despite greater Republican than Democratic support for the idea (91% vs. 70%) , a 2010 Gallup poll found that 80% of Americans subscribed to the notion that the U.S. has a “unique character that makes it the greatest country in the world.”

Boston University’s Prothero criticizes that definition of American exceptionalism, which he says is how most American politicians use the term today.

For John Winthrop, the shining city was an aspiration that depended on the righteous behavior of the Puritans, Prothero says, part of the social contract that laid the groundwork for democracy. Whether the city would in fact shine was an open question.

If the Puritans dealt falsely with their God, Winthrop had said in his 1630 sermon, there will be “curses upon us till we be consumed out of the good land whither we are going.”

In contemporary American politics, by contrast, Prothero says the idea of exceptionalism has been stripped of its conditionalism, becoming “a kind of brag.”

“Today, it’s ‘of course God blesses America,’ ” he said. “It’s presumptuous.”

Others have attacked the idea as little more than the kind of nationalism felt by citizens of countries all over the world.

“I believe in American exceptionalism,” President Obama said in France in 2009, “just as I suspect that the Brits believe in British exceptionalism and the Greeks believe in Greek exceptionalism.”

But the president has since sounded a different tune. In his Air Force Academy commencement speech in May, Obama repeatedly expressed support for American exceptionalism.

“The United States has been, and will always be, the one indispensable nation in world affairs,” Obama said. “It's one of the many examples of why America is exceptional.”

In fact, Obama appears to be the first sitting president to publicly use those words, political experts say. Given their place in the modern American political lexicon, nearly 400 years after Winthrop first gave voice to the idea, he is unlikely to be the last.