The biggest election in history has just been won by one man: Narendra Modi. Mr Modi has become the first Indian prime minister since 1971 to secure a single-party majority twice in a row. In 2014 the Bharatiya Janata party won an absolute majority in the lower house of parliament for the first time in its history after the Congress party’s appeal vanished in a haze of corruption. Despite a spluttering economy five years later, Mr Modi seems certain to have expanded his parliamentary majority. This is bad news for India and the world.

The BJP is the political wing of Hindu nationalism, a movement that is changing India for the worse. Little wonder, as it stands for the flagrant social dominance of the upper castes of Hindu society, pro-corporate economic growth, cultural conservatism, intensified misogyny, and a firm grip on the instruments of state power. The landslide win for Mr Modi will see India’s soul lost to a dark politics – one that views almost all 195 million Indian Muslims as second-class citizens.

On the campaign trail Muslims were denigrated as “termites” by Mr Modi’s right-hand man. Off it, they were lynched with apparent impunity. Despite their number, Muslims are political orphans, shunned by a political class fearful of losing support from the majority Hindu population. Before the election Muslims held just 24 seats in parliament, about 4% of the total, and the fewest the community has held since 1967. This is likely to shrink further.

A divisive figure, Mr Modi is undoubtedly a charismatic campaigner. Rather than transcend the faultlines of Indian society – religion, caste, region and language – Mr Modi’s style is to throw them into sharp relief. He is a populist who speaks in the name of the people against the elite despite being a seasoned public figure. Mr Modi deployed with terrible effect false claims and partisan facts.

Perhaps we ought not to be surprised. Polling in 2017 revealed that support for autocratic rule by a “strong leader” was higher in India (55%) than in any other country, including Vladimir Putin’s Russia. The world does not need another national populist. Mr Modi has threatened independent India’s most precious facet: a functioning multi-party democracy. As the authors of a new book on Mr Modi’s politics – Majoritarian State – put it, “the BJP has made it clear that no other party should compete with it … reflect[ing] its views of competitors not as adversaries, but as enemies”. Mr Modi recklessly chose to raise the stakes with neighbouring Pakistan over Kashmir earlier this year. He took both countries close to war and pressed conflict into his service by ridiculously accusing the opposition of collusion with fundamentalist Islam.

The Congress party and the Nehru-Gandhi clan that leads it will have to seriously rethink how they can defeat Mr Modi. The BJP has been allowed to be funded anonymously to the tune of 10.3bn rupees (£120m) by big business after Mr Modi legitimised opacity in political donations. The party pays lip service to reducing the yawning inequalities that disfigure India, but political cleavages in India’s party system have grown along the lines of caste and religious conflict. This suits the BJP, with its pro-business and anti-Muslim nationalism. The opposition will need to be able to run a distinctive campaign on an egalitarian platform. To be fair, Congress did peddle, but without much vim, a form of universal basic income. Fights over symbolic aspects of identity need to be replaced by political competition over how to benefit all Indians. That will require an opposition in India far savvier and more in touch with the country’s poor than exists today.

• This article was amended on 31 May 2019. An earlier version said that before the election India’s parliament had the fewest number of Muslim MPs in the lower house since 1952. This should have said 1967, and has been corrected.