London(CNN) In 2015, an obscure and rebellious backbencher named Jeremy Corbyn stunned the political establishment when his anti-imperialist, uncompromisingly socialist worldview lit a fire under the British left.

Suddenly, a man who wanted to dismantle NATO, nationalize British industry and called designated terrorist organizations "friends," was elected party leader by a grassroots caucus.

In the years since, Corbyn, who was already wildly popular in his own north London constituency, has developed a cult-like following among Labour members, with allegations of extremism, opposition to dissent and unelectability brushed aside by "Corbynista" acolytes. Now they hope that in two weeks' time he could be elected as prime minister in Britain's snap general election.

To those supporters, Corbyn is the remedy to political norms that have driven inequality and made the world less safe. Dawn Foster, a pro-Corbyn political commentator, says the Labour leader has "set himself apart from other politicians by saying things he believes in that might not be popular with the entire public."

But some Labour members believe their own party's leader is unfit to become prime minister. "Jeremy is instinctively opposed to all that has made our country great. From the Atlantic alliance that has kept the UK free to the competitive markets that have made us wealthy," says John McTernan, who worked for former Labour PM Tony Blair.

Onlookers may find it strange that a man who appears to hold views so at odds with the UK's status as a wealthy nuclear power could get anywhere near Downing Street.

However, since the Brexit vote of 2016, the UK is no longer a country that nods along to the status quo. And Corbyn's anti-capitalist ideas chime with many aching for something different.

"I think what lots of people have seen in Jeremy Corbyn is an authenticity that has been lacking in mainstream politics," says Wes Streeting, a Labour candidate running for reelection. A decade after the financial crisis, many in the UK are done with establishment politicians who they believe let bankers off the hook while normal people suffered savage austerity. Enter Jeremy Corbyn.

"Corbyn takes the complexity out of politics for a lot of people," says James Bloodworth, author and former Labour member. He explains that there is "a thirst in society for purity politics, where you don't have to compromise."

Jeremy Corbyn speaks on stage at Glastonbury Festival in 2017 where he received rapturous acclaim.

What shaped Corbyn's politics?

Before becoming Labour leader, not compromising or changing his mind was a luxury Corbyn could afford.

"You can really trace his worldview back to when he was a teenager," says Rosa Prince, author of the book "Comrade Corbyn: A Very Unlikely Coup." "He was very influenced by Vietnam. He went with his older brothers on marches in Trafalgar Square against Britain's possible participation in Vietnam." It was gatherings like this, Prince explains, that shaped Corbyn's ideology. "For so many years he was in this very small grouping of people on the far left and they all reinforced each other's views."

What exactly is that worldview?

"If someone hates the West their cause must be just. The more anti-West they were the more Corbyn would support them," says Leo McKinstry, who served as assistant secretary to Corbyn's constituency office in the 1980s.

A glance at 70-year-old Corbyn's past does little to dispel the "anti-West" charge.

In 1984, when he was a backbench MP, he invited two convicted IRA volunteers to the British Parliament, just two weeks after an IRA bomb killed five people at the Conservative Party's annual conference.

In 2004, he signed a motion that condemned the US-led intervention in the Kosovo war and downplayed the extent of the massacre of Muslims in Serbia.

In 2009, he invited members of Hamas and Hezbollah to speak at an event in Parliament, calling both organizations his "friends."

In 2013, he tweeted that Hugo Chavez showed "the poor matter and wealth can be shared," making no reference to accusations of human rights abuses or corruption in Chavez's Venezuela.

In 2014, he attended a ceremony at which wreaths were laid on the graves of four men believed to be behind the Black September terror attack at the 1972 Munich Olympics, where 11 Israeli athletes were murdered.

To critics, these are just five examples in a long list of controversies that prove his unfitness for office.

Fans say his willingness to engage with people shunned by the West is a realistic acknowledgment that peace only comes through dialogue.

Matt Zarb-Cousin, a former Corbyn spokesperson, explains that the Labour leader "obviously" isn't anti-West, but "against a type of US-dominated foreign policy that has led to illegal wars, the deaths of millions of people, and has made the world less safe."

But Corbyn's views on foreign policy and defense have caused him significant problems.

He previously said NATO was founded to "promote a cold war with the Soviet Union and should be disbanded."

He has faced criticism for not condemning leaders like Bashar al-Assad and Vladimir Putin for alleged war crimes in Syria.

In response to questions asked by CNN for this profile, Corbyn explained his foreign and defense policy via an official spokesperson.

"The Labour Party puts international justice and human rights at the heart of our international approach." On the matter of security and the UK's place in NATO, he said, "I will always do what is necessary and effective to keep British people safe, and I will not repeat the damaging mistakes of the bomb first, think later approach. We will play our full part in NATO but actively promoting our priorities for peace and security, not passively following American direction, as other Prime Ministers have done before."

Jeremy Corbyn acknowledges conference at the Labour Party conference in Brighton, England, in September 2019.

Latest scandal

Another area of foreign policy that has caused Corbyn problems is that during his years of campaigning for the rights of Palestinians, he's rubbed shoulders with an alarming number of anti-Semites. This has led to several accusations that the party is institutionally anti-Semitic, a scandal that has dogged Corbyn ever since becoming leader.

Rosa Prince believes that, over time, Corbyn's own views evolved on this subject. She says that in his time campaigning, Corbyn began to "conflate being Jewish with being sympathetic towards Israel and so sympathetic to Israel's policies towards Palestinians."

In 2012, Corbyn wrote a supportive message on Facebook in response to the street artist, Mear One, over a mural that was being removed by a London council.

The mural featured several anti-Semitic tropes, such as what are clearly supposed to be Jewish bankers playing a game of monopoly on the backs of the poor underneath the Eye of Providence, the universally recognized symbol of the Illuminati.

When the story emerged last year, Corbyn apologized: "I sincerely regret that I did not look more closely at the image I was commenting on, the contents of which are deeply disturbing and anti-Semitic."

It was far from an isolated incident. Only this week, the UK's Chief Rabbi took the unprecedented step of personally intervening in an election, writing that Corbyn's attempt to tackle anti-Semitism in the Labour Party was a "mendacious fiction," and that "a new poison -- sanctioned from the very top -- has taken root" in the party.

Supporters will remind you that Corbyn has always opposed anti-Semitism and all forms of racism. It's certainly true that Corbyn insists he is against racism and anti-Semitism. But it's also hard to ignore the fact that since 2015, he's rebuilt the Labour Party entirely in his image.

The centrism and pragmatism that gave Tony Blair's Labour Party a decade in power appears to be gone.

Blair, who won three elections, now even says he "understands" if people decide to vote for the opposition Liberal Democrats.

Boris Johnson and Jeremy Corbyn shake hands during a TV election debate on November 19, 2019.

Question of trust

But for all the negative focus on Corbyn's foreign policy, his popularity makes sense when you look at it from a domestic perspective.

Brexit has created space for Corbyn -- despite his longstanding Euroskepticism -- to present himself as the antithesis to Boris Johnson. Corbyn will offer you a second referendum on a softer Brexit deal and will take no deal off the table, protecting jobs. Somehow, the radical outsider now sounds like a reasonable moderate to many pro-Europeans.

He is also standing on an electoral platform that promises to tax the rich to pay for much higher public spending, something that chimes with voters weary of austerity. His critics say his plans are uncosted and a fantasy.

It helps that in 2019, Corbyn is able to define himself by what he's not, rather than what he is. Johnson is a wealthy man who led the Brexit campaign. Donald Trump calls Johnson his friend and talks up his desire for a UK-US trade deal. Trump also says that Corbyn would take the UK to "very bad places."

The US President's attacks feed the narrative that Corbyn is the more sensible man, standing up to recklessness and ego. Labour has been using Trump as a weapon, saying that Johnson would sell the National Health Service to Trump in exchange for a post-Brexit trade deal. Johnson has repeatedly said that the NHS would never be up for sale.

Suddenly, Corbyn looks like he could be the safer bet for pro-EU voters sick of political chaos. Bloodworth says that at rallies, he meets people "who say things like 'he's given me a reason to get up in the morning.'" However ridiculous that might sound, Corbyn leads Labour as trust in politicians is waning.

And it's this question of trust that British voters will be asking themselves ‪on December 12. Do they trust that Johnson, hellbent on delivering Brexit, will do so without wrecking the economy? Or do they trust a man who has spent his entire career on the political sidelines?

The UK is aching for political change and stability, after three years of chaos. Shelagh Fogerty, who hosts a phone-in show on LBC and regularly speaks to voters, explains that many are "tired of seeing bodies on the streets, stabbing rates off the scale, hospitals and social care on the brink, and millions in poverty."

At the moment, the chance of Corbyn entering Downing Street after the ‪December 12 election look remote. His party is trailing the Conservatives by more than 10 points in opinion polls, and Corbyn himself is the most unpopular opposition leader since polling began in 1977. However, his supporters point to the fact that late in the 2017 election campaign, he turned around a 20-point deficit to deny Theresa May's Conservatives an overall majority.

When voters enter the polling booths in a couple of weeks, they must choose between two men claiming to be the solution to the nation's greatest problem. The question is, which of them has the authenticity to convince voters that they are the answer?