NEW DELHI — Wearing Muslim skullcaps, colorful turbans of Indian Sikhs or hip beanies of secular university students, thousands protested at the largest mosque in India’s capital on Friday, a turbulent scene that played out in multiple cities across the country. They defied government curfews, internet shutdowns and the divisive politics that have kept them apart for years.
The unrest, now in its second week and increasingly violent, started over a contentious citizenship law that favors every other South Asian faith over Islam. It has since evolved into a broader fight over what demonstrators say is an increasingly authoritarian government bent on dismantling India’s foundation: a secular nation that draws strength from its diversity.
“You just needed a trigger,” said Jasbir Singh, a Sikh information technology worker who joined the protests in Bangalore this past week. “In India, religion never decided your citizenship, and it should not in the future.”
More and more people are pouring into the streets, and many have clashed with police officers. On Friday, six protesters were killed in several towns in northern India, according to officials and Indian news media reports, as officers used water cannons, tear gas, wooden sticks and possibly live ammunition against the demonstrators. At least 14 lives have been lost since the first protests erupted.
The protests have emerged as the biggest challenge yet to Prime Minister Narendra Modi and his agenda. His governing Bharatiya Janata Party has not shied away from articulating its vision of India as a homeland for Hindus.
Mr. Modi has tried to play down the diversity of the crowds, describing the protesters last Sunday as disgruntled Muslims and saying that they could be “identified by their clothes.” But the anger over the law is widespread, with Indians of various political stripes, creeds and backgrounds worried that one religion could become dominant.
It has galvanized university students, mirroring a pushback against conservative forces around the world. It has drawn in activists, intellectuals and professionals, continuing a long tradition of protests in India.
And it has prompted a global backlash. The United Nations and various rights groups condemned the law, while some American lawmakers called for sanctions.
“Those who want to implement discriminatory laws want to do a second partition, as if the millions dying in the first one wasn’t enough,” said Mr. Singh, the technology worker, referring to the bloody sectarian violence that unfolded in 1947 when the subcontinent was split, establishing India and Pakistan. “After seeing so many people protesting in Mumbai and Bangalore yesterday, I feel that old India is still alive.”
Protesters are also growing tired of Mr. Modi’s sectarianism as the economy sputters. At the polls, some Indians had put aside their apprehension of the prime minister, attracted to his economic plans. The country’s growth rate has now fallen to its lowest level in six years.
“A lot of people voted for Modi because of the economic issues and corruption. Now, the economy is in real bad shape and corruption has not gone down,” said Aadhira Gaikwad, 26, an advertising professional who protested in Mumbai. “All he is doing is using religion to hide under the real issues.”
“When the prime minister of this country says protesters can be identified by their clothes, it just fuels the fire,” Ms. Gaikwad added. “This is what he has done all these years.”
For India’s Muslim population, the protests are deeply personal. Muslims have watched the rise of Hindu nationalism under Mr. Modi with a wary eye.
Dozens of Muslims have been lynched by angry Hindu mobs, with the perpetrators often walking free. The country’s only Muslim-majority state, Jammu and Kashmir, was stripped of its autonomy in August, and thousands of young men and elected politicians were detained without being charged. And the Supreme Court, in a case known as “Ayodhya,” ruled that a temple could be built at the site where a centuries-old mosque once stood before a Hindu mob tore it down.
Until now, Muslims had largely remained quiet, hoping that sectarian relations could be restored. But when the government passed the citizenship law this month, many felt they had to mobilize or risk losing even more.
“We are at a tipping point now,” said Mohammad Abduzar, 26, from Merut in Uttar Pradesh State. “When Kashmir happened, when Ayodhya happened, no one questioned our citizenship. We were still first-class citizens. But how much longer do we have? How much further can this government push the envelope?”
Many Muslims fear that they could be stripped of their nationality. Along with the new law, the government also plans to expand a citizenship check nationwide. Those tests would force Indians to produce land deeds, birth certificates and other documents to prove their lineage in the country.
Panic recently set in when Mr. Abduzar and his father, Ahmad, realized that their names were misspelled on a school certificate and a passport. For years they had viewed the mistakes as nothing more than a nuisance, so commonplace that even bureaucrats dismissed the errors as the sloppy work of government clerks.
Now, such blunders could render them stateless. When the test was applied this fall in Assam State, about two million of its 33 million people failed, including a senior Indian military officer with a high-level government security clearance.
The new citizenship law would protect Hindus, Christians, Sikhs, Parsees, Buddhists and Jains who fail such checks. But Muslims, India’s second largest religious group, at 200 million, would be excluded.
India’s traditionally liberal-minded Supreme Court will hear challenges to the validity of the law in January. In the past, the court has thrown out many restrictive social policies, like a ban on gay sex, and has guarded privacy concerns. Critics say the citizenship law is unconstitutional because it discriminates based on religion, stripping away the state’s secular foundation.
Taken aback by the robust opposition, the government has tried to tamp down worries, insisting that Indian Muslims would not lose their nationality and that the law was aimed at providing a haven for persecuted religious minorities in neighboring countries. The citizenship test is necessary, the government says, to identify undocumented immigrants and ensure the country’s security.
“It is hypocritical for the government to be offering safety to religious minorities they say are persecuted, when they discriminate against their own, against Indian Muslims,” said Akhtarista Ansari, a 19-year-old university student in Delhi who is Muslim and was part of the protests this week.
Their criticism is rooted in the ideologies of Mr. Modi’s base.
Officials in his party and its powerful affiliates believe that minorities have been granted special protections at the expense of the country’s Hindus, who make up about 80 percent of the overall population of 1.3 billion. Many right-wing Hindus hold particular animosity for Muslims, as they were ruled for several centuries by the Mughal Muslim empire.
Sharad Sharma, a leader of Vishwa Hindu Parishad, an organization affiliated with the B.J.P. and classified by the Central Intelligence Agency as a Hindu militant group, said the days when the Indian government would appease the country’s minorities were over.
“Everyone living in India is a Hindu, including Muslims and Christians,” Mr. Sharma said, voicing a common right-wing refrain that all Indians were Hindus until they were forcefully converted.
“They have to be subservient to Hindus and Hinduism,” he added.
In this environment, conservative Hindus feel increasingly empowered.
When a Muslim was hired to teach Sanskrit at Banaras Hindu University, Hindu students protested, saying that it was improper for a Muslim to teach the primary liturgical language of Hinduism.
After another professor at the university, Shanti Lal Salvi, spoke in that instructor’s defense, he was attacked by students and had to flee the campus for his safety.
“There is a piousness everywhere, it is spreading and it is becoming very difficult to live in this atmosphere,” said Mr. Salvi, a Hindu. “This university was one considered a melting pot of ideas.”
“This kind of hatred now has an official sanction,” he said, “and it will only get stronger with every passing day.”
The wave of protests around India have left the government unprepared, and security forces have resorted to heavy-handed tactics to quell the demonstrations.
Hundreds have been detained. Opposition politicians and activists were arrested as they staged peaceful protests on Friday outside the house of Amit Shah, Mr. Modi’s right-hand man and the country’s powerful home minister, overseeing domestic security.
In an episode that was captured on video and disseminated widely on social media, five female students at Delhi’s Jamia Millia Islamia University rescued an unarmed male student the police were beating with wooden sticks last weekend.
While right-wing Hindus and governing party officials tried to paint the female students as radical Islamists, they conspicuously omitted that one was a Hindu. That student, Chandra Yadav, 20, studies Hindi literature and, like other secular Indians, also protested in opposition to the citizenship bill.
“This fight is not about Ram or Allah,” Ms. Yadav said, referring to a Hindu deity.
“This fight is for a state that is supposed to be for everyone, Hindu or Muslim,” she added. “As much as this country belongs to me, it belongs to Muslims.”
Jeffrey Gettleman and Suhasini Raj contributed reporting.