Donald Trump is an unlikely president. He is also an unlikely cultural warrior. That hasn’t stopped him from becoming both.

Besides throwing American politics into a tumult that won’t end in the near future, President Trump has reoriented and reinvigorated the American culture war. He has wrenched it away from its decades-long focus on issues related to religion and sexual morality and created another axis around populism and nationalism.

The issues involved in this new culture war – anti-elitism, political correctness, immigration, national sovereignty, multiculturalism – are every bit as charged as the ones that animated the old one. They involve the symbolically and emotionally fraught questions of how we should live and who we are as a people.

Other advanced countries don’t have culture wars quite like the United States. A fight has raged here since the 1970s over such issues as abortion, school prayer, traditional sexual mores, gay rights, religious displays on public property, pornography, graphic content in television shows and movies and school curriculums. The combatants have been, roughly speaking, secular coastal elites on the one hand and a religious heartland on the other.

Perhaps the high point for the right in the culture war came in 2004 when George W Bush, touting his support for a constitutional amendment banning gay marriage, won re-election on the strength of his support among evangelical Christians. Worried Democrats wondered how they could make inroads among these “values voters”. They haven’t had to worry since. Barack Obama’s election in 2008 heralded a new day.

If the old culture war wasn’t quite lost for the right, it was slipping away. Traditional marriage continued to decline, the entertainment culture got more coarse and old-fashioned sexual morality became the stuff of mockery. The rout on gay marriage has been so complete, with the supreme court making gay marriage legal throughout the land, that the left has moved on to the new cause of transgender rights.

Once, Democrats felt it necessary to play defence on social issues. No more. In an act that would have been unimaginable just a few years prior, the Obama administration got embroiled in litigation with an order of nuns – yes, nuns – on the question of whether they should have to technically abide by a federal contraception mandate or not.

Californians celebrate a supreme court ruling on same-sex marriage in 2015. Photograph: David McNew/Getty Images

In this context, Donald Trump is extremely ill suited as a culture warrior. The cliched charge against conservatives was always that they wanted “to impose their morality” on everyone else.

The wag might say that Trump is not threatening to impose his morality on anyone because he doesn’t have any to impose. He has bragged about bedding beautiful models. His marriages have exploded in spectacular fashion, providing endless fodder for tabloids. His religious literacy is extremely limited, at best, and he was comfortable for decades in a New York City that, besides San Francisco, is the nation’s foremost symbol of out-of-touch, decadent liberalism.

Five or 10 years ago, a Republican could have been forgiven for thinking that if Donald Trump jumped into the culture war, it would be on the other side. But Trump has changed the terms of the nation’s cultural contention.

He accepts gay marriage and has no interest in fighting over what bathrooms transgender people should use. On the other hand, he has been steadfastly anti-abortion, a function of coalition politics for him more than anything else. (Trump never would have won the Republican presidential nomination if he had remained pro-choice and evangelical Christians were a key Trump voting bloc in the general election.)

Trump is most vested in different battles, mainly against an establishment and a north-eastern elite that he considers overly insulated and self-interested and due to be taken down a notch.

All during his campaign, he inveighed against political correctness, whose enforcers on college campuses and in the elite culture have had the upper hand in establishing the agreed-upon rules for public speech. They had the power to make transgressors against their rules grovel, cry and apologise. To deny them their jobs. To make them worry about telling the wrong joke or posting an impermissible thought on Twitter.

Trump’s election, despite violating almost every rule set down by political correctness, represented a step toward the disempowerment of this elite.

His ongoing war with the media has to be seen through the same prism, as a tug of war for cultural power with an arm of the establishment. It is not unusual for Republican presidents to disdain, and complain about, the media. The ferocity of Trump’s daily fight with the press is different. It is more tribal and raw, a cultural clash that Trump’s team welcomes and intends to win.

Trump’s nationalism is another front in this war. A nation isn’t just a collection of people. It is a cultural expression – it has founding fathers, patriotic rituals and symbols, inspiring legends, traditional poetry and songs, a historical memory, military heroes and cemeteries.

In the United States, what the late political scientist Samuel Huntington called a “denationalised” elite has undermined these patriotic pillars. This elite has worked to submerge American sovereignty in multilateral institutions and treaties and undermine its national identity through multiculturalism and mass immigration.

President Trump’s unapologetic nationalism is a slap in the face to those political and business leaders who thought we were living in a “borderless” world. It is no accident that in his first week, Trump authorised the building of his famous border wall, an emphatic statement of American sovereignty, and prepared the way to begin enforcing the nation’s immigration laws more vigorously again.

A barrier already stands at the US-Mexico border. Photograph: Justin Sullivan/Getty Images

Immigration is so central to Trump because it involves the foundational questions of whether American citizens get to decide who comes here to live or not and whether the interests of American workers or foreign workers should be paramount.

The left had thought most of these questions were settled, or at least were inevitably bound to be decided in its favour. It believed, in the cliche it repeats over and over, that “history was on its side”. Well, Trump shows history is much less predictable than those who profess to speak in its name realise.

The great and the good assumed that Trump’s working-class supporters were dying off and would have a steadily declining influence in American politics. No one had to pay attention to them any more, as the world steadily became more cosmopolitan and integrated. These voters picked up on the disdain with which they were held and their instinct to hit back propelled the billionaire populist Donald Trump all the way to the White House.

Still not recovered from its shock, the left has had to grapple with the fact that it is living in a different country than it thought and that it is on its back foot in a new culture war it didn’t expect to have to fight.

Donald Trump is an unlikely cultural warrior, but if he can harness a sense of national solidarity and speak persuasively for ordinary American workers – while restraining his worst instincts – he may prove a powerful one.