The archbishop of Delhi has called for a prayer campaign until the next general election in an unprecedented political intervention, citing a threat to the country’s secular fabric, triggering angry reactions from the ruling Hindu nationalist party.

“We are witnessing a turbulent political atmosphere which poses a threat to the democratic principles enshrined in our Constitution and the secular fabric of our nation,” Archbishop Anil Couto wrote in a letter issued this month to all parish priests and religious institutions in the archdiocese of Delhi.

The letter became public this week, bringing to fore tensions between Christians and Hindu nationalist hardliners who form the bedrock of Modi’s Bharatiya Janata Party (BJP).

Christians constitute less than 3 percent of Hindu-majority India’s 1.3 billion people. India is officially secular, but four-fifths of its population profess the Hindu faith.

The BJP said the letter was akin to calling people to vote along communal lines, and that it was unfortunate. The next election has to be held by next May.

ANI television news agency quoted BJP minister Giriraj Singh as saying that “every action has a reaction”, while another BJP leader, Vinay Katiyar, said the archbishop’s comments could lead to “communal tensions”.

The spokesman for the Delhi Catholic Archdiocese, Father Savarimuthu Sankar, said the archbishop only called for a prayer campaign not an election campaign.

He said the letter, the first of its kind from Couto since he was installed as archbishop in 2013, was prompted by continued violence against Christians over the past four years and following attempts to bring back to Hinduism people who converted to Christianity.

“We try to influence at least those people who are educated, who are balanced,” said Sankar. “So far we have been saying these are fringe elements who are behind the attacks. But there is a danger that fringe elements may become the mainstream. To some extent they are succeeding also.”

The Evangelical Fellowship Of India, an alliance of evangelical Christians in India, said in a report in February that 2017 was one of the most traumatic years for the Christian community in India since Hindu-Christian clashes here killed more than 90 people, largely Christians, in the eastern state of Odisha in 2008.

The Evangelical Fellowship documented at least 351 cases of violence against Christians last year, mainly in states ruled by the BJP.

Responding to questions about the letter, Minister of Home Affairs Rajnath Singh told reporters that minorities are safe in India and that no one is allowed to discriminate on the basis of caste and religion.

Between 2014 and 2015, Couto and other Christians in the national capital region of Delhi told Singh how violence had picked up after Modi came to power, detailing at least five cases of attacks on churches in New Delhi following which extra police had been deployed to protect 240 churches in the capital.

Speaking at a event organized by the Catholic community in New Delhi after the church attacks, Modi vowed to protect all religious groups in the country.