NEW DELHI >> The novelist Nayantara Sahgal said she was returning India’s highest literary honor to express sympathy for "all dissenters who now live in fear and uncertainty." G.S. Bhullar, a short-story author, said he was giving back the same award to protest the "violent retrogressive forces dictating terms in the field of literature and culture." Mandakranta Sen, a Bengali poet, said she was sending her award back to protest "attacks on rationalists."

In the past month, 35 leading Indian authors and poets have returned coveted awards from the National Academy of Letters in a collective revolt against what Salman Rushdie last week called the "thuggish violence" creeping into Indian life under the Hindu nationalist government of Prime Minister Narendra Modi.

The writers’ revolt, which began in September after a 76-year-old critic of Hindu idolatry was gunned down in his home, gained strength this month after Modi failed to promptly condemn the killing of a Muslim man, Mohammed Ikhlaq, by a Hindu mob because they suspected he had killed a cow and eaten its meat.

The revolt now presents Modi with a critical test of his vaunted ability to shape the narrative of his administration. Perhaps more than any crisis he has faced since taking office 17 months ago, this one is offering a kind of X-ray of his carefully cultivated persona.

Just last month, during a visit to the United States, Modi was warmly embraced by Mark Zuckerberg and other Silicon Valley titans, who praised him as the modernizing, progressive, open-minded leader of the world’s largest democracy. But the backlash from some of India’s most celebrated writers underscores the extent of debate about the goals and essential nature of Modi’s administration.

Is he a Twitter-savvy technocrat obsessed with increasing development for India by slashing red tape, wooing foreign investors and building a modern digital economy? Or is he a canny ideologue intent on imposing a strict Hindu code of values on a nation that prides itself on tolerance, diversity and pluralism?

"Mr. Modi talks all these tall words abroad, on foreign soil," said Mangalesh Dabral, a poet who is returning his award from 2000. "All the sermonizing, this talk of the great digital India and the dreams he shows to people. All of it seems plain boasting because enactment of these tall words is invisible in his behavior and words inside the country."

One of Modi’s favorite modes of communicating is Twitter, where he has 15 million followers and more than 9,500 posts. On Twitter, Modi presents himself as cheerleader in chief for all things India, celebrating achievements, sending birthday greetings and offering condolences. Yet, as many commentators have pointed out, not one of his Twitter posts has offered condolences to the Ikhlaq family, which was brutally attacked by a Hindu mob last month in a village 30 miles east of Delhi.

With each passing day of silence from Modi, more writers have stepped forward to say that they, too, were returning their awards from the academy, also known as Sahitya Akademi. At least a dozen more writers have joined since Monday, when right-wing Hindu activists in Mumbai smeared black paint on the face of Sudheendra Kulkarni, a think tank leader, for agreeing to host a book launching for a former Pakistani official.

"There are attacks on ordinary liberties, the ordinary right to assembly, the ordinary right to organize an event in which people can talk about books and ideas freely and without hostility," Rushdie told India’s NDTV network on Tuesday. As if to prove his point, Rushdie described what happened when he posted on Twitter in support of Sahgal and the writers’ revolt, warning that these are "alarming times for free expression in India." Within hours, he said, he was besieged with thousands of outraged responses.

Uday Prakash, a renowned Hindi writer, was the first to renounce his award, in September. "I have never seen such hostility before," he said.

In interviews last week, the writers returned to the same refrain: That Modi’s failure to confront intolerance by fellow Hindu nationalists is giving tacit permission for more intolerance. "The tide of violence against freedom of speech is rising every day," Sahgal said.

On Tuesday, Modi for the first time directly addressed the Sept. 28 attack that left Ikhlaq dead. In an interview with the Bengali language newspaper Anandabazar Patrika, Modi called Ikhlaq’s death "really sad," and emphasized that his Bharatiya Janata Party, or BJP, "never supports such incidents."

But he also accused opponents of trying to exploit Ikhlaq’s death. "Opposition regularly alleges BJP of igniting communal flares," he said. "But isn’t the opposition doing polarization now?"

While Modi did not address the writers’ revolt, his allies have been merciless. Rakesh Sinha, an unofficial spokesman for the Rashtriya Swayamsevak Sangh, the ideological parent of the BJP, said the writers were "frustrated communist cadres" who had long opposed the "cultural nationalism" embraced by Modi’s supporters.

He noted that at least two of the writers who returned awards signed an open letter warning that Modi’s election as prime minister in 2014 would give rise to bigotry and violence. "They are not in a position to accept someone like Mr. Modi," he said.

In a post on Facebook, Modi’s finance minister, Arun Jaitley, ridiculed the protests as political sour grapes by leftist writers still reeling from "the shrinking fortunes" of their traditional government patrons, the Indian National Congress and the Nehru-Gandhi dynasty.

Several writers scoffed at the idea that the protests have a hidden political motive. Some pointed out that several writers were jailed during the state of emergency declared by Indira Gandhi in 1975. Rushdie, a British citizen who was born in India, wryly noted that it was the Congress party that banned his novel "The Satanic Verses" in 1988. "I’m not a fan of any political party," he said.

Few have drawn more criticism than M.M. Kalburgi, a rationalist scholar who enraged far-right Hindu nationalists through his criticism of idol worship and superstition. Kalburgi said he received death threats, and Aug. 30 he was shot dead in his home in Karnataka, in southern India. No arrests have been made.

A fierce debate rose among members of the National Academy of Letters after Kalburgi’s death. He had been a member of the academy’s general council, and he received an award from the academy in 2006. Yet it issued no formal statements condemning his murder.

Some members wondered whether the academy was quiet because it gets government funding. Sahgal criticized the academy for acting as if it was "wise to be silent when writers are being killed."

That silence is what led Uday Prakash to return his award. "Writers are a family, but they don’t seem to care," he explained.