The Christian Institute is threatening to take legal action against the UK Government over changes to the law on gay marriage in Northern Ireland.
Controversial same-sex legislation is due to come into force in the province in January but the Christian Institute is concerned that the forthcoming changes do not include many of the religious freedom and free speech protections in place in the rest of the UK.
Lawyers acting on behalf of the Christian Institute have written to Northern Ireland Secretary of State Julian Smith threatening legal action to protect religious freedom after the new legislation comes into effect.
The Christian Institute argues that legal protections for freedom of religion, expression and association must be included in the provisions on a part with the rest of the UK.
In particular, it wants to see provisions allowing for the conscientious objection of religious bodies and individuals like marriage celebrants and school teachers who believe that marriage is limited to one man and one woman.
Without these protections, they fear that school teachers may be compelled to promote or endorse same-sex marriage in the classroom, or that celebrants may be sued if they refuse to wed a gay couple.
If such protections are not implemented, the letter states: "Our clients will look to challenge by way of judicial review any failure to reflect the balanced treatment of the issues in a manner reflected in the same-sex marriage legislation in England & Wales and Scotland."
The letter cites the case of the Christian-owned Ashers bakery in Belfast, which was sued after turning down the order of an LGBT campaigner for a cake decorated with a pro-gay marriage design. Ashers won their case at the UK Supreme Court, which found that its actions were not discriminatory and that no one should be compelled to endorse a view they do not agree with.
Seeking clarification from the Northern Ireland Office on religious freedom protections in the forthcoming changes, a spokeswoman told the Christian Institute: "Parliament passed legislation which requires the government to put in place legislation to allow for civil same-sex marriage and opposite sex civil partnership in Northern Ireland by January 13 2020. We are working to meet this deadline."
Christian Institute spokesman Simon Calvert said: "Same-sex marriage is about to be legalised from 13 January and proper protections for those who disagree will not be in force. That's the implication of what the NIO says.
"Parliament took the best part of a year to debate introducing same-sex marriage in England and Wales. For Northern Ireland, MPs took only a couple of hours. In the rest of the UK there are many protections for those who disagree with same-sex marriage. Not so in Northern Ireland, with the Secretary of State and the NIO not seeming to be bothered.
"Churches must not be sued if they refuse to do a same-sex marriage. And public order law must be amended to stop church ministers being prosecuted for sermons that disagree with same-sex marriage. The new law has to make this clear.
"Guidance is also essential. In the rest of the UK, when same-sex marriage came in the GB Equality and Human Rights Commission issued guidance to make clear that: 'No school, or individual teacher, is under a duty to support, promote or endorse marriage of same-sex couples'.
"The CI is calling for protections for public sector workers, school children, churches, religious charities and the upholding of free speech."
The Christian organisation's call is being backed by pro-same-sex marriage campaigners, including Peter Tatchell, who told the News Letter: "The law in the north of Ireland should be the same as the rest of the UK."
Rainbow Project Director John O'Doherty said: "We, as with the position of the Christian Institute, believe that the protections in place in England and Wales should be extended to NI."
Patrick Corrigan of Amnesty International said: "We want the same protections and freedoms available in England and Wales to be available in NI."
