One of the most obscene moments after the death of the gang-rape victim in New Delhi was a tweet by Narendra Modi, the governor of the Indian state of Gujarat, offering regret and condolences to the dead woman's family.

Modi, who has quelled restive minorities by allowing attackers to subject women to unspeakable horrors, has done more than any man to numb his prudish country to sexual violence. Yet he was elected to a third term last month and is the presumptive front-runner of the Bharatiya Janata Party, the main Hindu opposition party, for prime minister in next year’s national elections.

So long as Indians keep rewarding politicos such as Modi, the country's collective outrage after the New Delhi case won’t change the culture that makes such atrocities common in India.

The attack on the 23-year-old physiotherapy student was truly depraved. Five men and a teenager in a private bus are accused of kidnapping, beating, raping, and violating her with an iron rod—and then dumping her and her semi-conscious boyfriend on a highway, where they also allegedly tried to run her over. But as horrific as this crime was, consider what happened in Gujarat in February 2002, a few months after Modi assumed office.

Organized bands of well-armed Hindus—some from groups tied to Modi’s party—fanned across the state seeking revenge against Muslims for allegedly burning a train full of Hindu pilgrims a few weeks earlier. The Hindu rioters systematically sought out and destroyed Muslim homes and businesses, killing more than 1,000 people.

Muslim women were singled out. According to many Indian and foreign sources, including a Human Rights Watch account and a report by an international research team called "Threatened Existence: A Feminist Analysis of the Genocide in Gujarat," women were stripped, gang-raped, often publicly, and finally in almost all cases burned or hacked to death.

The reason the violence reached such extremes was that the state police stood back and didn't intervene to stop the Hindu attacks and even told victims that it could not protect them. As if the bloodletting wasn’t horrific enough, Modi subsequently dismantled the shelters constructed by private organizations for dispossessed Muslims, calling them “child-breeding centers.”

Compared with the New Delhi rape, which has triggered a protest movement in India calling for the castration and execution of the suspects, the Gujarat rapes and pogrom elicited barely a whimper. Many Hindus either deny that the horror even occurred, or if they accept it, they claim it wasn’t as grisly as media accounts suggest. And if they believe the accounts, they say Muslims had it coming. Fewer than 100 out of the thousands of accused culprits—among them only one state minister and one Bharatiya Janata Party leader—were convicted, and that was a decade later. Modi himself was exonerated.

Whatever public disgust there was against him has dissipated, given the stellar economic growth that Gujarat has seen on his watch. Business leaders and corporations, from India and overseas, turn a blind eye to Modi's role in allowing the bloodshed, and praise his economic stewardship. His business backers have already managed to get the U.K. government to reverse its long-standing ban on him and to give him a visa. Now they are trying to persuade the U.S. government to follow suit.

What accounts for the wide gulf in the Indian public response to the single crime in New Delhi and the mass crimes in Gujarat?  

On the positive side, attitudes toward women have evolved considerably since the Gujarat atrocity more than 10 years ago. Thanks to liberalization, Indian women’s aspirations and opportunities have increased, especially in big cities, and they are demanding that the governing classes keep pace and create an environment in which they are free to move around safely.

After the New Delhi attack, any politician or even religious guru—no matter how revered—who suggested that women need to circumscribe their lives and choices for their own protection was condemned and lampooned, something scarcely imaginable when I was growing up in New Delhi (in a Hindu household) in the 1970s.

But the darker reality is that the young woman's rape and murder outraged the country’s Hindu urban middle class because it was a random and senseless act that could have just as easily victimized their daughters. Not so with attacks on the Muslim women in Gujarat. The premeditated and programmatic violence against them meant that the broader Hindu majority was insulated from it. If the New Delhi woman's fate made every Indian feel more vulnerable, the attack on the Muslim women made Hindus at some level feel more secure.

There are other reasons for India’s apathy toward Modi’s misdeeds. India is a democracy and has its share of human-rights activists and watchdog groups keeping an eye on government brutality. Yet the public at large has little appreciation of the dangers associated with overly muscular government. Indians complain bitterly about government dysfunction and corruption. Yet they have little compunction about giving draconian powers to their rulers in the name of security. The upshot, tragically, is that Indians care less about state-perpetrated rape than when perpetrated by individuals.

The scale of the sexual violence in Gujarat was unprecedented in India. But smaller episodes are a matter of routine. The Indian army has been accused of using rape as a weapon to crush secessionist movements in Kashmir and Manipur. After one particularly heinous case eight years ago, Manipuri women stripped naked and stormed the army headquarters with placards plaintively protesting: “Indian Army Rapes Us.”

Tolerating sexual violence for any purpose erodes the overall stigma against it, opening a moral space where tormentors can run amok. The lack of national outrage against the mass rapes perpetrated under Modi reduces their true cruelty, breaking down the psychological walls that would at least prevent nonsociopaths from going on a rampage. Hindus who turn a blind eye to the rape of Muslim women can’t ultimately protect their own.

How India can restore moral boundaries is a difficult issue, but it certainly won’t be solved by electing Modi to higher office—even if he were Adam Smith himself. Protesters shouldn’t just seek justice against the six accused in New Delhi. Modi, too, has much to atone.

An earlier version of this column appeared in Bloomberg View.