Judgment is due to be delivered on an appeal brought by Christian bakers who were found to have discriminated against a gay man.
Ashers Baking Company is seeking to overturn a previous court ruling that they acted unlawfully when they refused to decorate a cake with a pro-gay marriage slogan.
The high-profile case was heard before three senior judges at Belfast's Court of Appeal in May where it was claimed the outcome would have implications for freedom of expression across the UK.
During four days of technical legal argument, barrister David Scoffield QC, acting for Ashers, said the bakers could not have provided the cake because the message was inconsistent with their deeply held religious beliefs.
He said there was clear evidence Ashers believed it would have been "sinful" to have done so.
Meanwhile, a lawyer representing the Northern Ireland Equality Commission, which brought the civil suit on behalf of gay rights activist Gareth Lee, submitted that the firm had not been forced to do anything against its beliefs.
Robin Allen QC told the court many businesses printed messages they did not associate with, and cited examples of posters made for election candidates.
The appeal was lodged after a judge at Belfast's County Court found Ashers had breached equality legislation by refusing to provide the cake bearing the slogan "Support Gay Marriage".
Mr Lee, a member of the LGBT advocacy group Queer Space, had wanted a cake featuring Sesame Street puppets Bert and Ernie with the phrase Support Gay Marriage for a private function marking International Day Against Homophobia.
He paid the £36.50 in full at Ashers' Belfast city centre branch but was telephoned two days later and told the company could not fulfil his order.
In evidence, directors at the Ashers Baking Company in Belfast insisted they did not know what the sexual orientation of the gay rights campaigner was when declining his order.
Owner Karen McArthur said as a born again Christian, she knew in her heart she could not make the cake but had taken the order to avoid a confrontation in the shop.
Daniel McArthur, the company's general manager, also told the court his family could not compromise their religious beliefs, despite the legal ramifications.
Mr Lee claimed he was left feeling like a lesser person.
District Judge Isobel Brownlie said religious beliefs could not dictate the law and ordered the firm to pay agreed damages of £500.
An earlier appeal had been scheduled for February but proceedings were postponed to facilitate an intervention from Northern Ireland's Attorney General John Larkin QC, who advises Stormont politicians on legal matters.
In his submissions, Mr Larkin challenged the argument for "coerced expression" adding it was a "very great wrong" to make someone say something which conflicted with religious beliefs.
Ashers, a name with Biblical connotations, has six branches, employs over 80 people and delivers across the UK and Ireland.
Throughout the legal battle it has been supported by The Christian Institute, which has organised public rallies and garnered financial backing for the case.