Asia Bibi, the Christian mother sentenced to death in Pakistan for blasphemy, today had her final appeal postponed after years of languishing on death row.

The Supreme Court judge, Justice Iqbal Hameed ur Rehman, withdrew from the case because he had also overseen the appeal of Mumtaz Qadri, the man charged with – and eventually hanged for – the murder of Govenor of Punjab Salman Taseer in 2011, who had publicly defended Bibi.

"I was a part of the bench that was hearing the case of Salmaan Taseer, and this case is related to that," Rehman told the court in Islamabad.

He did not specify a new date for the hearing, and Bibi was taken back to jail.

So what happens next?

Bibi was first jailed in 2009 and sentenced to death in November the following year for allegedly blaspheming against the Prophet Muhammad during an argument with fellow farm workers. After her colleagues refused to drink from a cup used by Bibi because she was a Christian and therefore deemed 'unclean', she reportedly said: "I believe in my religion and in Jesus Christ, who died on the cross for the sins of mankind. What did your Prophet Muhammad ever do to save mankind?"

She was later pulled before a judge and convicted of blasphemy – a charge she has consistently denied. She was last year moved to solitary confinement in her prison in Multan, eastern Pakistan, over fears she may be attacked by vigilantes, and has been allowed to cook her own food for fear she will be poisoned.

Andrew Boyd of persecution charity Release International said today in the wake of the appeal's adjournment that it was unlikely Bibi's case would move forward quickly.

"She's been there [on death row] for six years," he told Christian Today, and her case is the most-high profile blasphemy case in Pakistan – arguably the most notorious the country has ever seen. More than 1,300 people have been charged with blasphemy in Pakistan since 1987, a disproportionate number of them Christians, but Bibi's case has captured world-wide attention, with international calls for her release and an end to Pakistan's repressive blasphemy laws.

In Pakistan, however, Muslim hardliners are desperate for her to be hanged.

A group of 150 top Muslim clerics from the radical Islamist group Sunni Tehreek issued a statement demanding the government hang Bibi and all other prisoners of blasphemy laws, World Watch Monitor said. The Muslim leaders reportedly issued a "verbal decree" that anyone who rescued or assisted in the rescue of people accused of blasphemy should also be killed.

Today, the cleric of the Red Mosque in Lahore said he would issue a fatwa against the Prime Minister of the country if Asia Bibi was set free.

The exact reason for the judge waiting until today to declare a conflict of interest that was previously known, is unclear. "What we do know," Boyd said, "is that there is an extreme climate of intimidation [in Pakistan]". More than 100 riot police were stationed around the court this morning to try to prevent violence, for which there is precedent in Pakistan. In addition to the assassination of Taseer, minority affairs minister Shahbaz Bhatti was also killed in 2011 for defending Bibi.

More than 60 people associated with blasphemy cases have been murdered in recent years, Boyd said, "so there's a climate of vigilantism, where many believe it is their religious duty to kill a blasphemer. If the court won't do it, they will do it."

It therefore takes immense courage to get involved in a blasphemy case, Boyd added. In earlier trials and appeals in Bibi's case, Islamic extremists packed out the courts in an attempt to intimidate the judge into upholding her death sentence. That's how it ended up being taken all the way to the Supreme Court; no judge has yet overturned the conviction, which campaigners say is probably – at least in part – because of threats to their own life by Islamists.

There was "overwhelming evidence" presented to the Lahore High Court, which held Bibi's earlier appeal, to overturn her conviction, said Wilson Chowdhry, chairman of the British Pakistani Christian Association (BPCA).

"Judges are being frightened, and it's preventing them from conducting this case in an appropriate manner, and bringing justice," he told Christian Today.

"It would seem this delay is completely contrived," he added, attributing the withdrawal of the judge today to the growing climate of extremism in Pakistan.

If it's not possible for the court to find a judge willing to take on the case, Boyd said, the President of Pakistan should issue an immediate pardon and set Bibi free. But this will be difficult given the rapid growth of Islamism.

"The blasphemy law is used like a can of petrol poured over the flames of extremism. It is used and abused to take over people's businesses and to seize land," Boyd said. "It will take enormous courage from the Preisident of Pakistan to pardon Asia, it will take enormous courage for the Prime Minister of Pakistan to repeal the blasphemy law, which has to happen. It will take enormous courage for the Supreme Court – short of a presidential pardon – to overturn Asia's case."

Bibi's earlier appeal in Lahore High Court was postponed five times, and there was a gap of around a month and a half between each postponed date, Chowdhry said. He urged the Supreme Court to set another date for her final appeal immediately, and a BPCA petition can be signed here.

"The longer this case simmers on the boil, extremists will be given the opportunity to make more noise, and gather more people against Asia Bibi," he warned. Each time her case was postponed previously, it "ignited Muslims, because they felt as though they were winning", he added. "Without a doubt, there will be a build-up of the number of extremists calling for her blood, the longer this case goes on.

"I'm praying the legal process in Pakistan is expedited as much as possible...Asia Bibi is only one innocent victim, there will be many more" until Pakistan revises its laws, Chowdhry said.

Boyd concurred. There are at least 16 other people on death row for blasphemy in Pakistan, and "if the Supreme Court were to rule that Asia should hang, it will be the thin edge of the wedge. Many others will die."

"This is a battle for the soul of Pakistan, which is a great, great prize," he added. "It won't come easily, and it won't come cheaply. We've seen in recent years an enormous rise in accusations of blasphemy. There was one case in 2011, and more than 100 in 2014. It all points to a rising intolerance that has to be addressed."

And yet, despite the growing persecution in Pakistan, and the death threats received by Bibi's family, their faith remains strong. Release International contacts have spoken to Bibi's husband, Ashiq Masih, who said his family is holding onto their faith, as is Bibi in prison, despite repeated attempts to convert her to Islam.

"They are courageous people who need our prayers," Boyd said. "What we are seeing [with Bibi] is a woman truly faithful unto death."