New Delhi, India - Christian groups have reacted strongly to a new law passed by the Indian state of Chhattisgarh which requires official approval of any religious conversion.
They said they were prepared to take the case to India's Supreme Court.
The General Secretary of the Chhattisgarh Christian Forum, Arun Pannalal, said they hoped to persuade the governor to withhold assent.
Mr Pannalal said the law contravened the fundamental rights of a citizen to freedom of thought and conscience.
Speaking from Raipur, he told the BBC that Christian groups had employed a similar strategy in Rajasthan which led to the governor refusing to give his assent to a similar conversion bill.
'Draconian law'
Mr Panalal said: "We will also go to the highest court if necessary to challenge this draconian law."
Chhattisgarh's Christian population has remained less than 2% since the early 1960s. The bill has been amended to say that "returning to one's forefather's religion or his original religion will not be treated as conversion".
Many see this as a means to allow the continuance of programmes promoted by right-wing Hindu organisations to reconvert Christians to Hinduism.
But Home Minister Ram Vichar Netam speaking in support of the law, said it was a common practice to change religion, especially in tribal areas, through force, lure or fraudulent means.
He said that because of these enforced conversions, it was necessary to amend the anti-conversion law to enable people to return to their original religion.
The bill asks for an application, from the person intending to convert and also the priest conducting the ceremony, to be put up before the district collector a month in advance with details as the date and venue of the ceremony.
Plans for sit-ins
The authorities will have the right to reject such an application.
The Christian Forum has announced plans to hold sit-ins and demonstrations from Monday to "educate people about the bill which is against the spirit of the Indian constitution".
Ravi Baksh, a Christian priest, said the new law had nothing to do with protecting Hindu religion but was a political game of Chhattisgarh's ruling party to please their masters.
Anyone violating this clause could be punished with a three-year jail-term and a fine or both.
Only a week ago another Indian state, Madhya Pradesh, also passed a similar legislation on religious conversion.
'Fascist agenda'
Rajendra Sayal, who has written extensively on religious conversion, called the bill "part of the larger fascist agenda of the right-wing Bhartiya Janata Party which considers Muslims, Christians and communists to be the biggest enemy of the Hindu state".
He said: "Since they also have a constituency to satisfy, they raise the issue of conversion through a sustained misinformation campaign by raising the bogey of large-scale conversion of Hindus by Christian missionaries."
The issue of conversion, especially to Christianity, has been one of the most emotive political issues in central India, and was even before India's independence in 1947.
Some princely states, now part of Chhattisgarh, passed anti-conversion laws as early as the 1930s.
The Vanvasi Kalyan Asharam was first established in the princely state of Jashpur to counter Christian missionary activity and to "awaken tribesmen of their true Hindu identity".