HYDERABAD, INDIA (NYTIMES) - India took a major step toward the official marginalisation of Muslims on Tuesday (Dec 10) as one house of Parliament passed a Bill that would establish a religious test for migrants who want to become citizens, solidifying Prime Minister Narendra Modi's Hindu-nationalist agenda.

The measure would give migrants of all of South Asia's major religions a clear path to Indian citizenship - except Islam.

It is the most significant move yet to alter India's secular nature enshrined by its founding leaders when the country gained independence in 1947.

The Bill passed in the Lower House, the Lok Sabha, a few minutes after midnight, following a few hours of debate.

The vote was 311-80. The measure now moves to the Upper House, the Rajya Sabha, where Mr Modi seems to have enough allies that most analysts predict it will soon become law.

Muslim Indians see the new measure, called the Citizenship Amendment Bill, as the first step by the governing party to make second-class citizens of India's 200 million Muslims, one of the largest Muslim populations in the world, and render many of them stateless.

The legislation goes hand in hand with a contentious programme that began in the northeastern state of Assam this year, in which all 33 million residents of the state had to prove, with documentary evidence, that they or their ancestors were Indian citizens.

Approximately two million people - many of them Muslims, and many of them lifelong residents of India - were left off the state's citizenship rolls after that exercise.

With the new citizenship Bill, Mr Modi's party says it is trying to protect persecuted Hindus, Buddhists and Christians (and members of a few smaller religions) who migrate from predominantly Muslim countries such as Pakistan or Afghanistan.

But the legislation would also make it easier to incarcerate and deport Muslim residents, even those whose families have been in India for generations, if they cannot produce proof of citizenship.

In Assam, where the citizenship program began last summer, thousands of people have marched in the streets, hoisting placards and torches and shouting out their opposition to the Bill.