Church leaders have united to voice their concerns over the implications of the Ashers court ruling.
After a judge said religious beliefs could not dictate the law, clerics warned the decision could set a dangerous precedent.
The Presbyterian Church in Ireland said it should profoundly concern everyone who wants a genuinely pluralist society.
Former Moderator Dr Norman Hamilton added: "Such levels of state control are surely contrary to the freedoms and liberties that we should seek to uphold.
"It is clear that the law needs to be changed. In a pluralist society, the law should protect everyone from discrimination while properly valuing the role of conscience.
"No one should be treated as a second-class citizen as we are all created with equal worth in the eyes of God."
The Presbyterian Church has backed a 'reasonable accommodation' concept in law.
Dr Hamilton added: "Whilst we recognise that this case has been a lengthy and painful experience for all of those directly involved, and troubling for wider society, we believe that there is an urgent need for an informed discussion about the role of conscience in the public square."
The Church of Ireland said that the ruling raised many important questions for society.
Rev Adrian Dorrian, Rector of St Mark's in east Belfast, added: "It is of some concern that the freedom of religious conscience that the law affords to all people may have been called into question.
"The owners of the baking company were upholding their adherence to the traditional Christian view on marriage.
"It is of real concern that a choice made by the owners of a business has been branded discriminatory and made the subject of legal action. Our society needs a debate around reasonable accommodation of differing opinion."
Henry Hull, the Dean of Down, wrote on Twitter he was "deeply disturbed" by the ruling. "Where is the freedom to follow Christian belief in an increasingly secular state?" he asked.
The Methodist Church said it noted the judgment with concern. Rev Dr David Clements added: "We have sympathy with the owners of Ashers bakery. If they are now compelled by the law to make products that conflict with their Christian conscience, this raises important issues."
The Free Presbyterian Church said the judgment followed "a ruinous trend" of pro-gay moves.
"Over the course of many years, the parliaments and courtrooms of our nation have increasingly legislated for sin and against righteousness," it added in a statement.
"Even allowing for this ruinous trend does not help us to understand how a judge in Belfast can reach a verdict that rules in favour of the promotion of an activity - same-sex marriage - that, by four successive votes in our legislative assembly, remains illegal in Northern Ireland."
The Catholic church was contacted for comment but did not respond.
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