The McArthur family, who last week lost a court case after a judge ruled that they had "unlawfully discriminated" against a gay rights activist, have confirmed that they will launch an appeal against the verdict.

"After much careful and prayerful consideration given to legal advice, we have decided to appeal the judgement handed down last Tuesday," the family, based in Belfast, said in a statement.

"We continue to insist that we have done nothing wrong as we have discriminated against no individual but rather acted according to what the Bible teaches regarding marriage.

"As many other people have already noted, Christian beliefs seem to have been trampled over in this judgement and we believe this only has negative effects for our society. Our hope and prayer would be that an appeal will allow us and other Christians to live out their faith in Jesus Christ in every part of their lives, including their workplace."

The McArthurs were ordered to pay £500 in damages to Gareth Lee, who took them to court after they refused to bake a cake decorated with a slogan supporting gay marriage. Judge Isobel Brownlie ruled that the company perpetuated "direct discrimination for which there is no justification".

"My finding is that the defendants cancelled this order as they oppose same-sex marriage for the reason that they regard it as sinful and contrary to their genuinely-held religious beliefs," Brownlie told the court.

"The defendants are not a religious organisation. They are conducting a business for profit and, notwithstanding their genuine religious beliefs, there are no exceptions available under the 2006 regulations which apply to this case."

The case has divided opinion over religious freedom, however, and the McArthurs have stood by their decision not. General manager Daniel McArthur said after the ruling: "We're extremely disappointed with the judgment. We've said from the start that our issue was with the message on the cake, not the customer and we didn't know what the sexual orientation of Mr Lee was, and it wasn't relevant either.

"We've always been happy to serve any customers that come into our shops."

The family's appeal is being supported by The Christian Institute. Spokesman Simon Calvert said: "I believe that most people think that this is a ruling that should be overturned.

"There has been such extraordinary support from people from all walks of life who are appalled by what has happened to the McArthur family. There is huge public support for an appeal and it is vitally important that the higher courts consider this issue."

A ComRes poll taken in March of this year found that 90 per cent of voters in Northern Ireland believe equality laws "should be used to protect people from discrimination and not to force people to say something they oppose", Calvert added.

"In the same poll, nearly four out of five (79 per cent) believe a Muslim printer should not be taken to court for refusing to print cartoons of Mohammed. And almost three quarters (74 per cent) believe a printing company run by Roman Catholics should not be forced by legal action to produce adverts calling for abortion to be legalised.

"But this is what awaits us if this judgment is allowed to stand."