The history of the group, and its close ties to both Pakistan intelligence operatives and Saudi financing, might go some way to answering that.
Ishaq was last released from jail in September after a brief detention, related not to terrorism but for what authorities termed "provocative speech."
After that, his group, Lashkar-e-Jhangvi (LeJ), allies of al-Qaeda and the Taliban, continued its long-running killing spree.
But nothing matched the magnitude of the death toll of their bombings in the western Pakistan city of Quetta on Jan. 10 and Feb. 16, which left at least 96 and 89 people dead, respectively.
The vast majority of the victims were Shia from the Hazara ethnic group, part of an ongoing campaign of violence and intimidation by Sunni Muslim militants.
LeJ has been carrying out such attacks since 1996 but this latest violence is pushing Pakistan further into crisis.
"Pakistan is already on the edge of a precipice: killings, mayhem, and the breakdown of state control spread across the country, while the government seems to ignore it all," Pakistani journalist and best-selling author Ahmed Rashid writes in his latest book, Pakistan on the Brink.
Rashid estimates that in 2010 and 2011, "Sunni extremists killed more than 500 Shias, many of them Hazaras."
Last year, more than 400 Shias were killed by Sunni extremists, many of them Hazaras in Balochistan province, according to Human Rights Watch. Quetta is Balochistan's capital.
'The most dreaded sectarian outfit'
LeJ, described as "the most dreaded sectarian outfit in Pakistan" by the South Asia Terrorism Portal, is considered the militant group that's most responsible for these killings.
Lashkar means army and Jhangvi refers to Maulana Haq Nawaz Jhangvi, one of the leaders of the political party Sipah-e-Sahaba Pakistan (SSP), who was killed in 1990.
LeJ is considered the armed wing of the SSP by several organizations that monitor terrorism activity. Ishaq told Reuters last year that he's a leader of the SSP.
LeJ also has links to the Taliban, al-Qaeda and other Sunni militant groups in Pakistan.
Many of its leaders were part of the mujahedeen who fought the Russians in Afghanistan in the 1980s. During the Taliban's rule, LeJ operated a training camp near Kabul.
From the beginning, LeJ's primary targets have been Pakistani Shia, while Iranians and Iranian interests in Pakistan were their second choice. By 2001, they were believed responsible for at least 350 violent incidents.
After the fall of the Afghan Taliban in 2001, the group is said to have targeted Pakistani officials, including the attempted assassinations of then-president Pervez Musharraf and two prime ministers.
The U.S. government has said the group was also involved in the kidnapping of American journalist Daniel Pearl (who was subsequently beheaded by one of his captors).
It has also been implicated in a bombing in Karachi that killed 16, including 12 French nationals, and another bombing near the U.S. consulate in Karachi that killed 12 people, all in 2002.
Ottawa added LeJ to Canada's list of terrorist organizations in 2003.
In 2011 LeJ expanded its range of attacks to Afghanistan, killing 59 people in a bombing at a Shia shrine in Kabul and at a second bombing in Mazar-i-Sharif, the worst sectarian attack in that country since 2001.
LeJ's Ishaq in and out of prison
In 1997, Ishaq told the Jang newspaper group that he had been "instrumental in the killing of 102 human beings."
He spent the next 14 years in custody on numerous charges but was released in 2011 because prosecutors could not prove the accusations, due in part to the killing of about a dozen witnesses.
Reuters reports that he was "showered with rose petals by hundreds of supporters when he left prison."
In addition to Ishaq, LeJ's founding triumvirate included Riaz Basra and Akram Lahori. Basra was killed in 2002 and Lahori was arrested in 2002 and is still in custody.
Employs social media
Reuters news agency visited Ishaq at his home in Punjab province in October 2012. They reported a sign on the gate that was an invitation for people to come debate whether Shia Muslims are infidels.
For Ishaq, that would be an understatement. He told Reuters that the Shia are the "greatest infidels on Earth," adding that they "should be given a death sentence" for insulting "the companions of the Holy Prophet."
LeJ wants to get rid of Pakistan's Shia community, which comprises about 20 per cent of the population, and transform the country into a Taliban-style Sunni state.
The Punjab-based LeJ began attacking Quetta's Hazaras in 2001.
To carry out it's anti-Shia hate campaign, LeJ often uses social media.
It's main vehicle is the Jhangvi Media Movement, which has the website jmmpak.org, as well as other associated websites and forums, and a Facebook page.
The English-language article with the most hits on jmmpak.org is titled, "Is Shia Muslim???"
The group also employs Twitter (handles include @Jhangvi, @Jhangvinews and @SunniKilling), Scribd and YouTube, according to The Middle East Media Research Institute.
One of their YouTube videos declares that, "the [Shia] is the offspring of the Jews."
Operates with impunity
In December, New York Times correspondent Declan Walsh reported from Quetta about "sectarian death squads that openly roam these streets."
"The killers strike with chilling abandon, apparently fearless of the law: shop owners are gunned down at their counters, students as they play cricket, pilgrims dragged from buses and executed on the roadside," he wrote.
A retired Hazara engineer told Walsh, "if the government is not supporting these killers, it must be at least protecting them. That's the only way to explain how they operate so openly."
Human Rights Watch agrees. In its 2013 World Report, the London-based group says that, in Pakistan, "religious minorities continued to face insecurity and persecution as the government failed to provide protection to those threatened or to hold extremists accountable."
According to HRW, "the government was unable or unwilling to break the links between Pakistan's military and intelligence agencies with extremist groups.
"Sunni militant groups, including those with known links to the Pakistani military, its intelligence agencies, and affiliated paramilitaries, such as the ostensibly banned Lashkar-e Jhangvi, operated openly across Pakistan, as law enforcement officials turned a blind eye to attacks.
"The government took no significant action to protect those under threat or to hold extremists accountable."
Arrests a government ploy?
After the Feb. 16 bombing, Pakistani authorities finally took action against LeJ, arresting 170 people they accuse of being involved in the attacks.
However, the arrests "have been looked upon warily as nothing more than a ploy to placate an angry nation," according to Pakistan's Dawn newspaper.
Ayesha Siddiqa, a Pakistan security expert and author of Military, Inc., writes that, "the LeJ and other militants have always been and remain conduits of state actors."
She says because the military perceives Shias as close to Iran, possibly working for Iran, and since the army can use LeJ as their proxies, they ignore LeJ's brutality.
Pakistan has long been seen as a battlefield in a proxy war between Saudi Arabia and Iran, the dominant Sunni and Shia powers. Washington believes that LeJ and related militant groups receive funding from Saudi sources.
A secret cable released by Wikileaks, dated Dec. 30, 2009, from then secretary of state Hillary Clinton says, "Saudi Arabia remains a critical financial support base."
She adds that, "some officials from the Pakistan's Inter-Services Intelligence Directorate (ISI) continue to maintain ties with a wide array of extremist organizations."