Narendra Modi’s landslide victory as prime minister of India in 2014 was borne on his promises to unleash his country’s economic potential and build a bright future while he played down the Hindu nationalist roots of his Bharatiya Janata Party.

But, under Mr. Modi’s leadership, growth has slowed, jobs have not materialized, and what has actually been unleashed is virulent intolerance that threatens the foundation of the secular nation envisioned by its founders.

Since Mr. Modi took office, there has been an alarming rise in mob attacks against people accused of eating beef or abusing cows, an animal held sacred to Hindus. Most of those killed have been Muslims. Mr. Modi spoke out against the killings only last month, not long after his government banned the sale of cows for slaughter, a move suspended by India’s Supreme Court. The ban, enforcing cultural stigma, would have fallen hardest on Muslims and low-caste Hindus traditionally engaged in the meat and leather industry.

It would also have struck a blow against Mr. Modi’s supposed priorities: employment, economic growth and boosting exports. The $16 billion industry employs millions of workers and generated $4 billion in export income last year.