Charges against an Indian intellectual who has defended Christians' rights highlight how toxic any non-Hindu faith is in India, a senior Church figure has told Christian Today.

Bishop Joseph D'Souza, the Moderator Bishop and the primate of the Good Shepherd Church of India as well as being founder of the Dalit Freedom Network, says the sudden surge in hostility to activist and writer Kancha Ilaiah should concern all Christians as he warned churches would be next.

Kancha Ilaiah, 64, faces charges, branded an 'absurd assault' on free expression by Amnesty International, for his book Post-Hindu India and his latest work Samajika Smugglerlu Komatollu ('Vysyas are Social Smugglers') and could face up to five years in jail.

The book criticises India's caste system and in particular the Vysya, or business caste, who absorb vast proportions of the country's wealth leaving the lower castes destitute.

Last month he was attacked by a mob in the Warangal district of Telangana, central India, and he has also faced death threats including one member of India's parliament saying he 'should be pubilcally hanged' as well abusive anonymous phone calls.

'Many unknown phone calls kept coming and when I answered they abused me. The International Arya-Vysya Sangham headed by K Ramakrishna condemned my writings on a TV channel. Someone threatened to cut my tongue. My effigies have been burnt. I feel terribly threatened by their abuses, phone calls and messages. If anything happens to me they will be responsible,' he said according to the Indian Express.

But the storm of abuse does not just concern a debate around the Indian caste system.

Ilaiah has spoken for Christians' right to freedom of expression, including defending a rally organised by evangelist Franklin Graham in 2011. Bishop D'Souza warned that behind the abuse was animosity towards Christians.

Allegations made by Hindu extremists against Ilaiah claim he has a Christian agenda behind his writing and such is the toxicity of that label that he was forced to put out a statement dismissing the claims.

'One of the recurring accusations of the recent Arya Vysya agitators and their associate Paripurnanada Swamy, a hater of St. Mother Theresa and Christian human service, against me is that I have a Christian agenda behind my writing,' he said.

'This is absolutely false,' he added, explaining he only had academic connections to primary schools educating poor children that have Christian links.

Now Ilaiah's opponents have used a number of Christians to attack him themselves in an attempt to divide loyalties among the church, D'Souza claims.

Such is the strength of feeling that the former employer of one Christian critic, Albert Lael, felt obliged to disown him.

Lawrence Tong, international director of OM International, said: 'OM International does not condone the allegations and activities directed against Kancha Ilaiah or the Good Shepherd Schools by Albert Lael, a former employee of OM India.'

But for D'Souza what on the surface is an internal controversy among India's political class is actually a broader threat that could soon hit the Church.

'What concerns me is that freedom of expression as a fundamental human right in India is not undermined,' he tells Christian Today.

'The danger to Christians and all people who believe in freedom of expression is that a couple of months ago it was Gauri Lankesh [a prominent female journalist murdered by a gunman outside her house last month], now it is Kancha Illiah. Tomorrow it could be me. Any major figure speaking on what is constitutionally my right can be knocked off by these groups.'

D'Souza does not direct his criticism at Prime Minister Modi's nationalistic ruling party, the BJP. But he warns their agenda and drive to make India a Hindu state is legitimising other fringe groups that are hateful of minorities like Christians as well as being violent.

'I am not saying the government is doing it but these people now feel empowered,' he says.

'A narrative is being creative that Christians are anti-national which is absolutely wrong. We are as national as everybody else.

'Colonialism definitely has contributed to it. But Indian Christians have not contributed to it.'

The effect of this narrative amid India's atmosphere of increasing Hindu nationalism means for anyone to be branded as having a Christian agenda or Christian links can be fatal.

'The way these opponents of freedom of expression are working is if anybody is trying to reform Hinduism from within, they say he has got a Christian agenda. They make it look anti-national. So you immediately put the person on the defensive as if there are no Indian Christians.

'But the accusation that the West is involved is totally wrong.'

D'Souza says despite the threats and concerns, Christians must not go on the defensive and pointed to the Indian Supreme Court's refusal to ban Kancha's books as a sign of hope.

'We don't need to be on the defensive but there are issues we need to deal with,' he says. 'India is a free country and it is still a great democracy so we don't need to be on the defensive.'

But he adds: 'Non-engagement now by Christians in societal matters is not an option.'