They have terrorised religious minorities, incited riots against France, and mobilised thousands of fanatical supporters who have paralysed Pakistan with violent protests at a moment's notice.
In just five years the Tehreek-e-Labbaik Pakistan party (TLP) -- whose leader, Saad Rizvi, was released from detention on Thursday -- has seen its reach explode in Pakistan, opening a new chapter in the country's deadly confrontation with extremism.
The party, also known as the Movement at the Service of the Prophet, launched a campaign against France after Paris-based satirical magazine Charlie Hebdo last year republished cartoons depicting the Prophet Mohammed -- an act deemed blasphemous by many Muslims.
But the TLP first began making headlines in 2016, when they protested the execution of Mumtaz Qadri, a bodyguard who assassinated the governor of Punjab over his stance on blasphemy, a massively inflammatory charge punishable by death in Pakistan.
Many saw Qadri as a hero -- a sentiment which gave the TLP's founder, Saad Rizvi's father Khadim Hussain Rizvi, an opening to turn the group "into a movement," analyst Khurshid Nadeem told AFP.
- Not a 'small subset of bigots' -
The next year, the TLP forced federal law minister Zahid Hamid to resign after virtually paralysing Islamabad with a weeks-long sit-in.
That shocked observers, who wondered at the young group's ability to bend the Cabinet to their demands.
Rizvi, they realised, had weaponised blasphemy and radicalised swathes of Punjab, Pakistan's most populous province.
Pakistan is no stranger to extremism, but previous movements -- such as the Pakistani Taliban -- have largely been based in the minority Deobandi sect.
The TLP, however, has its ideological roots in Barelvi Islam -- a mainstream sect traditionally seen as moderate, but for whom blasphemy is a red line.
Pakistan's blasphemy laws "have become fully internalised by and ingrained in the population; that is the sentiment that the TLP uses to draw support," said Madiha Afzal, a fellow at the Brookings Institution.
"It would be a mistake to assume TLP's support base is limited to a small subset of bigots," added Michael Kugelman, a South Asia expert at the Washington-based Wilson Center.
- Fears of backlash -
In 2018, protests by the TLP brought the country to a standstill once more after Asia Bibi -- a Christian woman accused of blasphemy -- was acquitted.
That same year the party won more than two million votes in a general election.
Then Charlie Hebdo magazine reprinted the cartoons, stirring outrage once again in Pakistan.
By April this year, the protests against France had become so dangerous that Paris warned its citizens to leave Pakistan.
The group was banned, but that order was lifted on November 7 after the government struck a deal with the party that it said was in the "national interest" after seven police officers were killed during a fresh round of rallies that began last month.
Rizvi's release comes on the eve of the first anniversary of the death of his father