Fascists and other far-right extremists are set to assemble in Warsaw tomorrow for a march that has become one of the largest gatherings in Europe, and perhaps beyond, for increasingly emboldened white supremacists.

The march, held on Poland’s 11 November Independence Day holiday, has drawn tens of thousands of participants in recent years. Extremists from Sweden, Hungary, Slovakia and elsewhere now join Polish nationalists in a public display of xenophobic and white supremacist views, since the event began on a much smaller scale in 2009.

The slogan for this year’s event is “We Want God”: words from an old religious Polish song that President Donald Trump quoted in July while visiting Warsaw. Trump praised Poland for what he described as the country’s defence of Western civilisation.

Rafal Pankowski, head of the anti-extremist association Never Again, says that despite the reference to God, the march shouldn’t be viewed as inspired by religious beliefs. Far-right “neo-pagans” plan to take part along with Roman Catholic groups.

“We know that Donald Trump is not the most religious man, and I think that most of the organisers are not very religious, either,” Pankowski, a sociologist, said. “But they use Christianity as a kind of identity marker, which is mostly about being anti-Islam now.”

The Warsaw march has grown so large it might be the world’s biggest assembly of far-right extremists, he said.

The organisers include the National-Radical Camp, the National Movement and the All Polish Youth, radical groups that trace their roots to antisemitic groups active before World War II.

In a sign of the rally’s international reach, American white supremacist Richard Spencer was scheduled to speak at a conference in Warsaw on Friday – until the Polish government said Spencer wasn’t welcome in the country. The far-right conference is still being held.

The emergence of Central Europe as a crucible for neo-fascism carries a number of paradoxes. The region, once stuck behind the Iron Curtain, has seen impressive economic growth since Poland, Hungary and other countries threw off communism, embraced capitalism and joined the European Union and NATO.

Few of the Muslim refugees and migrants who have arrived in Europe since 2015 have sought to settle in that part of the continent, preferring Germany and other richer countries in the West. Nonetheless, anti-migrant views run high.

Political scientist Miroslav Mares, an expert on extremism at Masaryk University in the Czech Republic, said Central Europeans hear about attacks by Islamic extremists in France, Germany and England and fear that “beyond the borders is a state of chaos and war” that could envelop them.

While extremist movements often thrive during hard times, the quality of life is better than ever now in a region that has known wars, occupation and oppression.

“Central Europe is living the happiest time in its history,” said Grigorij Meseznikov, president of the Institute for Public Affairs, a think tank in Slovakia. “Never was life in this region as prosperous as it is today.”

But like others in the era of globalisation, many people feel frustrated that the improving economy hasn’t benefited them. There are complaints that wages remain much lower than in the West while inequality has grown since the end of communism.

“If you look at Slovakia, the situation 25 years ago was much worse. There was high inflation and unemployment higher than 20 per cent, yet we didn’t have a fascist party in the parliament,” Meseznikov said. “Today, we really have a functioning economy, low inflation, declining unemployment; we are in the EU and Nato ... And nevertheless there are fascists in the parliament.”

Mares thinks a lot of the disappointment stems from a tendency by Czechs and their neighbours to compare their financial situations to those of Germans and others in the West, rather than looking east to much poorer Belarus and Ukraine and feeling encouraged by how far they have come.

The frustrations, combined with a souring mood toward established elites, have helped far-right parties in recent elections in Germany, Austria and the Czech Republic. In Poland and Hungary, right-wing governments promote tough anti-migrant policies and historical whitewashing to glorify their nations.

Meseznikov also sees Russia’s encouragement of anti-European Union and anti-American views that spread on social networks as part of a “toxic mixture” behind the growth of the far-right.

It could be years before the tide ebbs and reverses, according to Polish expert Pankowski.

Sociological data show that the generation of Poles that has only known democracy is more prone to xenophobic and far-right nationalism than their parents’ generation, with younger Poles paradoxically “turning their backs on democratic values,” he said.

“I think many of them will keep those far-right views inside them for decades to come,” Pankowski added. “It’s not an issue that will disappear.”