Release International is urging people to sign its petition on religious freedom in India following the passage of anti-conversion laws in several states.
Madhya Pradesh has just passed legislation requiring anyone wanting to change their religion to obtain permission from the authorities first.
Converts who fail to report their change of faith could face up to three years in prison, or four years if they are a minor, woman or a Dalit.
Anti-conversion laws have been passed in seven Indian states due to pressure from Hindu nationalists who believe that being Indian is to be Hindu, Release reports.
Release partner, the All India Christian Council, has launched a legal challenge against the anti-conversion laws.
"Release International is deeply concerned about the rise of Hindu extremism and the growing culture of religious intolerance in India," says Release Chief Executive Paul Robinson.
"We will be presenting a petition in November calling on India to uphold the religious freedom guaranteed under its constitution."
The Release petition points out that freedom of conscience and the right to practise any religion are guaranteed by Article 25 of the Indian Constitution.
In contrast to the protection promised, the petition notes that Christian pastors and evangelists are being "frequently" attacked by Hindu extremists and detained by police on false charges of forcing people to convert. This is particularly the case in rural Karnataka and Andhra Pradesh.
The petition goes on to ask the Indian government to put a stop to the attacks and bring the perpetrators to justice, as well as uphold the right of Christians to practise and propagate their faith without fear of false accusations and imprisonment.
Mr Robinson urged people to go online and sign the petition.
"We need to show India that Christians around the world are watching and we care," he said.
The tightening of anti-conversion laws has come at a time of increasing attacks on Christians. According to former high court judge Michael Saldana, there have been 1,000 instances of persecution against Christians since 2010 in Karnataka state alone.
In other areas, memories of attacks by rampaging Hindu nationalists are still fresh. Orissa was the scene of terrible violence in 2008 when mobs killed more than a hundred Christians and forced 50,000 from their homes. More than 4,000 homes were destroyed in the violence.
"Attacks on Christians in India are definitely increasing," says Joseph D'Souza, the council's president. "These attacks take the form of physical violence, destruction of churches, false cases and arrests. They are co-ordinated."