Madhya Pradesh has become the latest state to pass a law banning religious conversions.
The law came into force in the central Indian state on 9 January, following closely from Uttar Pradesh which introduced a similar law last November.
Release International, which supports persecuted Christians around the world, fears the development is another step towards Christian evangelism being banned across the entire country.
Anti-conversion laws have been passed in at least nine states across India, but Release's partners in the country warn that the Madhya Pradesh legislation is particularly tough, permitting police to arrest suspects without warrant and holding them without bail, with the onus on the suspect to prove their innocence.
The law states: "No person shall convert or attempt to convert, either directly or otherwise, any other person by use of misrepresentation, allurement, use of threat of force, undue influence, coercion or marriage or by any other fraudulent means."
Release warned that while the law on paper is intended to prevent conversion by force, in practice it criminalises Christians distributing aid.
Since the passing of the anti-conversion law in Uttar Pradesh, a South Korean Christian and three Indian nationals have been jailed after distributing food aid to people affected by the Covid-19 lockdown.
"On the face of it, that may seem reasonable, but these laws are catch-alls which simply fuel intolerance and extremism," said Release CEO Paul Robinson.
India was one of the countries of concern in Release's recent Persecution Trends report warning that the mistreatment of Christians there is likely to worsen this year.
Robinson said the anti-conversion movement reflects the rise of Hindu nationalism in India - an ideology based on the concept of 'Hindutva', which equates being a Hindu with being an Indian.
Hindu nationalism has grown since the BJP came to power in 2014, and Christians in the country have warned of increasing numbers of attacks.
In September, a mob of up to 3,000 people attacked Christians in three villages in Chhattisgarh – another state to have passed an anti-conversion law.
"The move to prevent conversions in India is partly a reaction against growing numbers of the Dalit underclass responding to Christianity," Mr Robinson continued.
"These are the so-called untouchables. Many see them as fated to carry out menial tasks, such as cleaning lavatories or sweeping the streets.
"Unsurprisingly, many Dalits are responding to the Christian message of love and acceptance."
He called on India to repeal the anti-conversion laws.
"It seems under these anti-conversion laws you are guilty until you can prove your innocence," he said.
"These are dark days for the world's largest democracy. Freedom of religion and belief are a cornerstone of all freedoms – and guaranteed under the Indian constitution.
"Any attempt to remove that right is a violation of the constitution that safeguards the world's largest democracy."