Gay rights campaigner Peter Tatchell has criticised an Appeal Court ruling that found against a Christian bakery which refused to make a pro same-sex marriage cake.
Ashers Bakery in Belfast has counted Mr Tatchell as one of the more unlikely supporters of its court bid to challenge a ruling that found it was discriminatory in rejecting an order for a cake bearing the slogan Support Gay Marriage.
He said the Appeal Court judgment that upheld that ruling had set a "dangerous, authoritarian precedent", claiming gay bakers could now theoretically be compelled to bake cakes carrying homophobic slogans.
The high-profile activist originally denounced Ashers for declining the cake order.
But during the long legal saga that has followed that episode in 2014, Mr Tatchell had a change of heart.
He has since argued that while he profoundly disagrees with Ashers' views on gay marriage, he supports the Christian bakers' contention that they should not be forced to endorse a message that runs contrary to their beliefs.
"This verdict is a defeat for freedom of expression," he said.
"As well as meaning that Ashers can be legally forced to aid the promotion of same-sex marriage, it also implies that gay bakers could be forced by law to decorate cakes with homophobic slogans.
"It seems that businesses cannot now lawfully refuse a customer's request to propagate a message, even if it is a sexist, xenophobic or anti-gay message and even if the business has a conscientious objection to it.
"Although I strongly disagree with Ashers' opposition to marriage equality, in a free society neither they nor anyone else should be compelled to facilitate a political idea that they oppose."
He added: "Discrimination against LGBT people is wrong and is rightly unlawful. But in a free society, people should be able to discriminate against ideas they disagree with. I am saddened that the court did not reach the same conclusion.
"The judgment opens a can of worms. It means that a Muslim printer could be obliged to publish cartoons of Mohammed and a Jewish printer could be required to publish a book that propagates Holocaust denial. It could also encourage far-right extremists to demand that bakers and other service providers facilitate the promotion of anti-immigrant and anti-Muslim opinions.
"What the court has decided sets a dangerous, authoritarian precedent that is open to serious abuse.
"Discrimination against people should be illegal but not discrimination against ideas and opinions."