Narendra Modi, the chief minister of the Indian state of Gujarat, looks extremely likely to become India's next prime minister — his party, the BJP, has already won 280 of 545 seats, giving them an outright majority and a huge political victory — and the international community is terrified. Though Modi is running as an economic fixer, or "India's CEO," The Economist went so far as to issue an anti-endorsement, urging Indians to vote for anyone but Modi.

So who is Narendra Modi? And why is the world so worried?

Who is Narendra Modi?

Modi is a leader in the Bharatiya Janata Party (BJP), India's second-largest political party, which according to exit polls just won a landslide victory after ten years of rule by the incumbent party Indian National Congress Party (or Congress for short). Unless the exit polls prove badly mistaken, Modi will become prime minister.

Modi is known for his trim beard, stern demeanor, and imposing rhetorical style. He is currently the top political official for Gujarat, a northwestern state with about 60 million people, and has been since 2001. He is also a member of the right-wing Hindu nationalist group Rashtriya Swayamsevak Sangh (or RSS). He has been a member of the RSS for nearly four decades — an important detail for reasons explained below.

Modi campaigned on two major platforms. The first is economic management: he positions himself as India's CEO. While India’s economy has slowed over the last four years, Gujarat's economy has done well enough for many Indians to see Modi as a leader able to cut through India's notorious bureaucracy and corruption, and return the country to double-digit growth. The second platform, which is less openly stated but just as important, is right-wing Hindu nationalism — a major concern for India's Muslims, not to mention outside observers who see it as a recipe for disaster.

Why are people so worried about Modi?

He has a notorious record for ginning up religious tension in a country where this can be — and often is — deadly. And his ascent coincides with a rising trend of Indian right-wing Hindu nationalism that has stirred up major concern among many foreign observers. That concern is so pronounced, The Economist ran a cover story explicitly urging Indian readers to vote against Modi. "By refusing to put Muslim fears to rest, Mr. Modi feeds them. By clinging to the anti-Muslim vote, he nurtures it," the article warned. The anti-endorsement was, like just about everything Modi, extremely controversial in India.

What is Hindu nationalism?

Hindu nationalism is a movement of right-wing nationalism combined with a Hindu political identity so strong that its ultimate end has been described as, if not Hindu supremacy, then Hindu hegemony to the detriment of the 20 percent of Indians who are not Hindu.

India’s constitution declares the country to be secular and there is a tradition of celebrating and embracing religious diversity. However, India’s history is also marred by clashes between people of different religious backgrounds — particularly Hindus and Muslims.

There is a specific incident that people often cite when talking about Modi's Hindu nationalism: the 2002 riots in Gujarat. A year into Modi's tenure running the state, mass Hindu riots broke out against Muslims and an estimated 1,200 people, most of them Muslims, died in the violence. Many reported the police of the state did nothing to stop the attacking mobs, and Modi and his government have long been accused of allowing, and potentially abetting, the riots.

This is not a fringe conspiracy theory: the US State Department denied Modi a visa to visit the US in 2005 over his suspected role in the incident.

A few months after the riots, New York Times reporter Celia Dugger asked Modi if he wished he handled the riots any differently. He told her his greatest regret was not handling the media better. Dugger said in a Times video interview that Modi did not show "any regret or [express] any empathy for those who had been slaughtered in his state, on his watch."

The 2002 riots were years ago. Why does it still matter?

While tragic, the 2002 riots are merely one reason for the international distrust of Modi. He has made a habit, and in some ways a career, of anti-Muslim rhetoric. He's accused political opponents, for example, of being "Pakistani agents." The RSS, of which he is a member and which has endorsed him for prime minister, has been repeatedly banned in India for inciting or causing political or religious violence. The party has grown more moderate in the last few years, but its core Hindu nationalist mission hasn't changed, and neither has Modi's.

While Modi has scaled back the rhetoric that's drawn so much criticism in the current campaign, there are still flashes of it — perhaps in part because he needs Hindu nationalists' votes. For example, he's made speeches condemning India's beef export industry. This may sound innocuous, but within India it's a clear dogwhistle aimed at the Indian Muslims who dominate the beef industry, and meant to stir up Hindus who find beef consumption religiously objectionable. As the Financial Times pointed out, it's exactly the kind of rhetoric that has led to communal violence in the past.

More worryingly, a video has surfaced showing Modi's top lieutenant at a private election gathering in a part of India that has seen recent Hindu-Muslim violence. He told the Hindus gathered that voting for Modi would lead to "honor and revenge" for the killings.

"This is the time to avenge," he said. It's like Mitt Romney's 47 percent video, except instead of belittling welfare recipients the Indian official appeared to be hinting at religious reprisal killings.

What makes Modi's rhetoric so dangerous?

The thing you have to understand is the devastating pattern of Hindu-Muslim violence that has recurred in India since 1947, when the partition and independence of the British Raj created the nations of Pakistan and India: one country for Muslims, another for Hindus. About 10 million people who lived on either side of the divide relocated to the country of their religion. Over one million people died in communal violence and a Hindu-Muslim wound opened that has not yet healed.

Many Muslims did remain in India after 1947, and on the vast majority of days and in the vast majority of cities there is no violence between Hindus and Muslims who live side by side. However, there's enough fear and mistrust on both sides and violence has erupted over the years, often precipitated by growing religious tensions. Modi does not just inflame that religious tension; he personifies it.

Why are so many Indians supporting Modi, given his reputation?

There are a few reasons. He and his party have a large support base among the urban middle class, which is growingly rapidly. The party that's been in power for most of India's history, the Congress Party, is increasingly seen as corrupt and inept. But the big issues are economic growth and Hindu nationalism.

First: economic growth. Modi has been running India's Gujarat state since 2001, during which time its economy has grown substantially. This Quartz deep-dive on Gujarat's numbers argues that the growth isn't quite the miracle story that BJP says it is, but many Indians support Modi because they believe he has a proven track record of economic success at a time when India's overall growth is slowing, and they have real grounds to believe that. This chart shows India's economic growth slowing significantly in 2012, as Modi rose:

The other big reason for Modi’s popularity is Hindu nationalism. Yes, the thing that makes Modi so worrying is also what makes him so popular. Some significant chunk of BJP supporters really like Modi’s nationalism and want to see more of it. He's not just stirring up religious tension and virulent nationalism because he likes those things personally; he's being encouraged to do it by his popular support base. That's what makes all of this frightening: a Modi prime ministership isn't just a threat of greater religious tension and nationalism, it's the culmination of those forces by popular mandate.

What would Modi's foreign policy look like?

Modi’s campaign mainly has focused on domestic issues, but as prime minister he would run Indian foreign policy at a time when it's increasingly important. His anti-Muslim rhetoric, and his past accusations that political opponents are "Pakistani spies," suggests he would worsen rather than improve relations with Pakistan. The two countries are armed with nuclear weapons, have frequent and ongoing disputes, and have fought several wars, most recently a 1999 conflict that got dangerously close to open nuclear warfare.

Modi's party has already suggested it may revise the country's "no first use" policy, by which India promises not to launch nuclear weapons except to defend against a nuclear attack. In other words, a Modi-run India would lower its standards for nuking another country.

It's tough to say what his relationship with the US would be like. The fact that the State Department refused him a visa to visit in 2005 doesn't bode well. Nor does the rising nationalist sentiment in India, which often portrays the US as unfairly maligning India, and has in past months put Indian politicians under tremendous pressure to pursue confrontation with the US over cooperation. Modi's nationalist temperament and support base will make him more likely to indulge these populist outbursts. On the other hand, Modi's record of emphasizing trade and economic growth suggests he'd rather get along with the world's richest country.

Still, that's all hypothetical. The safest bet is probably that Modi would emphasize trade with China and southeast Asia, as he's done in his time running Gujarat. And it is often, though not always, true that nationalist leaders who are fire-breathing populists at home will push more pragmatic foreign policy abroad.

Okay, but what actually happens if Modi becomes prime minister?

The fears about a Prime Minister Modi are more general than they are specific. More Hindu nationalism means more anti-Muslim sentiment, which could potentially mean more religious violence within India and more popular anger toward the mostly-Muslim Pakistan. Both of those are already huge problems for India, as they lead to violence, instability, and catastrophic incidents. While Hindu-Muslim tension and violence within India are nothing new, they certainly have the potential to get worse if the government encourages those tensions, which Modi has an alarming track record of doing.