On January 22, Indian Prime Minister Narendra Modi consecrated the Ram Mandir, a vast new Hindu temple in Ayodhya. Cast as “the high priest of Hinduism,” in the words of his biographer, Modi gave offerings and blessings to an idol of Lord Ram, one of the most revered Hindu deities, who was supposedly born on this sacred spot. The temple is also a powerful political symbol for Modi and his ruling Bharatiya Janata Party: it was built on the ruins of a sixteenth-century mosque that Hindu-nationalist mobs, egged on by BJP leaders, demolished in 1992, sparking sectarian riots that left 2,000 people dead.

Modi promises to create a “new India,” by which he means a Hindu India, where the country’s more than 200 million Muslims will be seen as interlopers. In fact, this deliberate mixing of religion and politics is unconstitutional in India. Independent India’s first prime minister, Jawaharlal Nehru, as well as the political and spiritual leader Mahatma Gandhi, recognised how explosive religious strife could be in a multi-faith and multi-ethnic society, which is why they insisted that India be a secular state.

The desire to undermine the secular state long precedes Modi. The man who murdered Mahatma Gandhi was a member of the Rashtriya Swayamsevak Sangh, a paramilitary Hindu nationalist organisation with ties to the BJP that played a major role in the razing of the mosque in Ayodhya. In 1986, Hindu agitators seized upon then-Prime Minister Rajiv Gandhi’s misguided decision to give into Muslim demands to permit Islamic law to override a Supreme Court ruling upholding the right of Muslim divorcées to receive alimony beyond 90 days. Using this exception to whip up smoldering Hindu resentments, these agitators pushed Hindu nationalism from the margins to the centre of Indian politics.

Alas, Modi is not alone in embracing this brand of religious politics. Unlikely as it may seem for a foul-mouthed sexual predator, former US President Donald Trump is being branded by his followers as a saviour of Christendom, who will cleanse the United States of leftists, feminists, gays, immigrants, liberal elitists, and other sinners. A promotional video recently posted on Trump’s website, Truth Social, leans into this narrative, claiming: “God had to have someone willing to go into the den of vipers. Call out the fake news for their tongues as sharp as a serpent’s. The poison of vipers is on their lips. So God made Trump.”

Evangelical Pentecostalists, as well as reactionary Catholics, now believe that Trump is more than a political figure. The former president was anointed by God to make America great again. Yes, he is being prosecuted for assaulting a woman, overturning an election through violence, and committing fraud, but that shows how he is a martyr persecuted by evil enemies, just like Jesus Christ.

Religious politics are the greatest threat to democracy, more than social or economic inequality, lying politicians, or corruption, all of which are bad enough. Liberal democratic institutions exist to resolve conflicts of interests. Disputes over taxation, land use, farm subsidies, and so on, can be settled through argument and compromise between political parties. Sacred matters, however, cannot. God’s truth is non-negotiable.

That is why a militant religious group like Hamas cannot be a democratic political party. In a radical Islamic state, there is no room for debate or compromise. The same goes for Israeli religious extremists who believe their rights are justified by the Bible. Water rights are debatable; sacred land is not.

The point is not to try to cure humanity of religious beliefs. The desire to submit to a higher authority, to believe in life beyond death, to divide the world into believers and non-believers, to revile sinners and worship saints, and to celebrate life’s stages with holy rituals is a universal human trait. But such desires belong in churches, temples, synagogues, and shrines, not in political discourse. Religious and political authority must not overlap.

Nehru understood this. Thomas Jefferson understood this. And many Christian leaders, especially Protestant ones who didn’t want the secular state to encroach on religious affairs, understood it, too. Catholics have had more of a problem with the separation of church and state, but most have learned to live with it.

The reason why so many democracies are now threatened by messianic politics is not because organised religion has gained in strength. In fact, I think the opposite is true. In most Western democracies, at least, church authority has almost entirely collapsed. This is true even in the US: While most people still consider themselves to be believers in one faith or another, many American Christians, especially those who are drawn to Trump as a saviour, follow freelance preachers or spiritual entrepreneurs.

In many parts of Europe, where right-wing populism is on the rise, the erosion of church authority starting in the 1960s cast adrift people who used to go to church regularly and looked to their priests and pastors to tell them how to vote. Today, they are anxious and bewildered by demographic, political, social, sexual, and economic changes, and are seeking a saviour to lead them to a simpler, more certain, and more secure world. There are plenty of power-hungry demagogues more than willing to cater to this desire.

Buruma is the author, most recently, of The Collaborators: Three Stories of Deception and Survival in World War II.

–Project Syndicate