John Avlon is a CNN senior political analyst. The opinions expressed in this commentary are his own. View more opinion articles on CNN.

(CNN) Polarization is killing our country. It is weakening our political and social bonds, separating our economic fortunes and driving bitter cultural divides.

Hyper-partisanship is poisoning our politics, making our democracy seem increasingly dysfunctional. A fixation on our differences is fracturing us into warring tribes, threatening to turn our country into little more than a collection of grievance groups who believe that folks on the other side of the divide are the ones really tearing our nation apart.

This is not the American way. It is the opposite of the secret of our success, summed up by our national motto, e pluribus unum -- "out of many, one."

Healing our divided nation is the defining challenge of our time. Because nothing less than the success of the American experiment is at stake.

If you think polarization is getting worse, you're not alone. Exit polls from the 2018 midterm elections showed that 76% of voters believe our country is becoming more divided . A new Pew survey shows that over 60% of Americans believe both parties have become "too extreme." And 87% of Americans say political polarization is threatening our way of life.

As the political becomes personal, a quarter of committed conservatives and liberals say that they would be unhappy if a member of their immediate family married someone outside their political party, according to Pew . This interpersonal intolerance is metastasizing into something much darker: A 2019 study found that just over 42% of both parties view the opposition as not just mistaken but " downright evil ."

No wonder a sense of civic despair is kicking in: large majorities of Americans believe that the country will only become more divided in their lifetime.

Polarization in the age of Trump

Polarization has accelerated under President Donald Trump because of his callous disregard for democratic norms, interpersonal decency and even truth itself. He is instinctively a divider rather than a uniter, a demagogue who demonizes anyone who tries to hold him accountable. But he is a symptom of our polarization, not its cause.

His peculiar political position is a prime example. Trump is the only president in the history of Gallup polling never to have been above a 50% job approval rating. Current CNN polls show that 50% of Americans now support his impeachment and removal from office. But because Trump remains popular within the increasingly polarized Republican Party, he has the power to intimidate conservative critics into silence because they fear having the base turn them out of office in a closed partisan primary. It follows that his campaign's reelection strategy isn't to unite the nation and win by the largest possible margin, but to win an electoral vote victory by demonizing the Democratic opposition as radical socialists who hate America.

It's important to understand that this is counter to the way most US presidents have tried to govern and the way most elections are won. But this negative partisanship threatens to become the new normal.

How we got here

The founding fathers tried to warn us about the dangers of polarization. George Washington devoted a majority of his Farewell Address to what we would call hyperpartisanship, warning that, "It agitates the community with ill-founded jealousies and false alarms, kindles the animosity of one part against another, foments occasionally riot and insurrection. It opens the door to foreign influence and corruption."

John Adams was characteristically even more blunt, saying "there hasn't yet been a democracy that didn't die by suicide." A generation later, Abraham Lincoln echoed these concerns by saying "as a nation of freemen we must live through all time or die by suicide."

Self-government can never be taken for granted. But we can take comfort from the fact that America has been through far worse trials -- the Civil War and the Great Depression -- and we have ultimately emerged stronger and wiser.

In the mid-20th century, for example, the greatest generation provided political ballast born of shared experience -- from the Great Depression and serving in World War II. The fact of ideological diversity within the two parties, with progressive Republicans and conservative Democrats, ensured that even in times of divided government, America could get big things done though bipartisan coalitions, from the Marshall Plan to the interstate highway system to landmark civil rights bills -- all while winning the cold war over communism.

But over the past quarter century, the two parties have become more polarized along regional, racial and ideological lines. Beginning with the 1994 Republican Revolution, we saw a stark divide between the two parties reflected in congressional voting patterns with fewer and fewer legislators backing bipartisan legislation. This destructive dynamic was reinforced by the rigged system of redistricting which dramatically reduced the number of competitive congressional elections and drove power to the extremes.

Total obstruction has become the norm for opposition parties, as ideologues and activists disproportionately dominate the national debate. Declining trust in democracy is exacerbated by the fact that our elected representatives can't seem to agree on anything even when confronted with a crisis like climate change, or when compromises are clear on issues like immigration reform and infrastructure, or even when vast majorities support specific solutions like expanding background checks amid rising gun violence.

At the same time, the rise of partisan media turned play-to-the-base polarization into a business model, enabling people to self-segregate into separate political realities. Social media has balkanized us further, amplifying the loudest voices, often manipulating perceptions of public opinion via anonymous bots and trolls while driving many reasonable people from the public square of civic debate. No wonder that a new Pew survey shows that 73% of Americans now believe that Republicans and Democrats cannot agree on basic facts. This is a recipe for disaster because democracies depend on the ability to reason together.

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Our adversaries understand that polarization is America's Achilles heel. That's why Russia specifically targeted America's deepest divisions in their 2016 social media campaign. They disproportionately targeted white nationalists and black nationalists, stoking fears about Muslims, guns and illegal immigration while supporting the two most populist and polarizing candidates on the other side of the aisle, Bernie Sanders and Donald Trump.

As the most recent report from the bipartisan Senate Intelligence Committee stated: "operatives consistently used hot-button, societal divisions in the United States as fodder for the content they published through social media in order to stoke anger, provoke outrage and protest, push Americans further away from one another, and foment distrust in government institutions."

Some American activists on the far right and far left found themselves duped by Russian efforts. In one infamous case, Russian Facebook pages spurred competing protests on different sides of the same street outside a mosque in Houston. In some ways, that's a perfect metaphor for the dangers of polarization -- it's a fear-fueled feedback loop between activists who are easily manipulated into presenting a more divided vision of America than actually exists.

The global stakes

These dynamics are more dangerous because they are happening on a global scale. Polarization has also led to deep division and political paralysis in two of our closest allies -- Great Britain and Israel. While liberal democracy seemed to be ascendant 30 years ago with the fall of the Berlin Wall, ethno-nationalist autocracies have been on the rise this decade, with Russia and China leading a backlash to globalization that offers tribal pride at the expense of pluralism and promises wealth without liberty. It is a vision fundamentally at odds with the diverse liberal democracy that America, at its best, represents on the world stage.

But America's current stress test is having an effect -- Freedom House has gauged America as becoming less free, warning that "We cannot take for granted that the institutional bulwarks against abuse of power will retain their strength, or that our democracy will endure perpetually. ... Rarely has the need to defend its rules and norms been more urgent."

It's time to defend our democracy

If our enemies see that polarization and identity politics is our greatest source of weakness, it should be clear that we need to rise above these divisions and re-assert this fundamental American truth: for all our interesting differences, there is more that unites us than divides us.

There is still time to redeem something positive out of this period of poisonous polarization. Because an increasing number of Americans realize that we have taken our democracy too much for granted. There is a growing demand for something different, a turn away from polarization toward reunification as a nation.

Independent voters have skyrocketed over the past 30 years as the two parties have gotten more polarized, according to Gallup. There are more self-identified independent voters than Republicans or Democrats, while moderates outnumber liberals and often conservatives.

While our politics are disproportionately dominated by special interests, most Americans want the two parties to find ways to work together in the national interest. But in the absence of adult behavior, more than 60% of Americans say that both political parties are out of touch with the country, while 57% say there is a need for a major third party . And according to nonprofit organization More in Common, 93% of Americans say they are tired of how divided we have become.

Moreover, we know that hardcore partisans' perceptions of the other party are wildly off-base -- for example, according to a study by More in Common, Democrats believe that only half of Republicans recognize that racism still exists in America while Republicans believe that only half of Democrats are proud to be American. In reality, eighty percent of Republicans understand that racism remains an issue in America and eighty percent of Democrats say they are proud to be an American.

Our challenges will not be solved in a single election cycle. But they can be solved if committed individuals begin building a broader citizens' movement dedicated to defending our democracy by combating the larger forces dividing us as a nation.

Some of the political changes to combat polarization are clear -- redistricting reform, open primaries and ranked choice voting -- all of which can adjust the incentive structures away from the extremes. More ambitious solutions may require building a strong coalition between the center-left and center-right or even eventually the creation of a third party.

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But the problem of polarization is bigger than politics and to address its root causes we need to bridge our economic and cultural divides.

The American Dream requires the right to rise based on equality of opportunity and hard work -- and that social contract must be repaired. The middle class has been squeezed with stagnant wages and lower social mobility for decades. Small businesses struggle as big businesses get massive breaks. The hollowing out of mid‑sized manufacturing cities in America's Heartland has helped to fuel the rise of populism on the left and right.

We need to pursue policies that counteract the forces that conspire to divide us. At a time when 7 in 10 Americans say that our country is in danger of losing its national identity, we need to reassert a common understanding of our shared history -- warts and all -- by reinvesting in civic education again. This includes teaching the importance of vibrant civil debate consistent with the first amendment, without the expectation of "safe spaces" that do not exist in the real world. It's not too much to ask that every graduating high school student be able to pass the same citizenship exam that new immigrants take. This may be controversial to some, but as Congressman John Lewis said , "Maybe our forefathers and foremothers all came to this great land in different ships, but we're all in the same boat now."

It may also be time to re-examine a return to national service in a variety of forms, from military service to teaching (like AmeriCorps), the Peace Corps, the National Park Service or work in local government in exchange for an expanded new G.I. Bill of rights that can make college education and vocational training more affordable without saddling students with crippling debt.

The good news is that we are not as divided as our hyperpartisan politics suggest. The culture of our country did not change on election day in 2016. The red state vs. blue state narrative is too simplistic -- the real divisions we confront are rooted in the differences between urban and rural America. After all, Hillary Clinton won most large cities in the South and a recent survey showed the two most popular governors in America right now are blue state Republicans , Charlie Baker of Massachusetts and Larry Hogan of Maryland. To find our common purpose, we must define our common ground and then consciously build upon it.

The first step in solving a problem is admitting you have one. If we clearly name the problem afflicting our nation -- polarization -- we can begin to take concrete steps to overcome it.

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We can do this armed with the knowledge that we are defending core American values -- because e pluribus unum is literally the opposite of "Us against Them," the demagogue's eternal calling card. There is no "them" in the United States. There is only us -- imperfect people working to form a more perfect union and making fitful progress with each generation.

Our independence as a nation is inseparable from our interdependence as a people -- and now more than ever, we must transcend our tribalism to survive.