- British taxi driver Alan Henning was delivering aid to Syria when he was abducted
- Friends, colleagues and British Muslim leaders have asked ISIS to release him
- ISIS, which now controls large parts of Syria and Iraq, has beheaded several Western hostages
On Christmas Day last year, Alan Henning was sitting in a brightly lit cafe in southern Turkey, sharing a laugh with his friends before they set off on their journey.
Henning, a big-hearted taxi driver from Bolton, northern England, was part of a team of volunteers traveling from Britain to Syria to deliver aid to people in need.
Nicknamed "Gadget" by his peers, Henning was the only non-Muslim in the convoy. He sacrificed Christmas, weekends and family time to do his part for those worst hit by Syria's civil war, and was admired by his fellow volunteers.
This was the father-of-two's fourth trip to the war-torn country. While part of the aid convoy stopped at the Turkish border, Henning was part of a much smaller group that volunteered to press ahead into Syria itself.
In video shot on the day, he explained part of his rationale for answering the call to help. "It's all worthwhile when you see what is needed actually gets where it needs to go," he said, before hugging a colleague.
Henning was kidnapped by ISIS a day after the video was made. He is now under threat of imminent execution.
As the clock ticks down, those who made the trip with him are pleading with the leaders of the militant group -- which has declared an independent Islamic state across parts of Syria and Iraq -- to let Henning go.
"Alan was moved by the suffering of the Syrian people, in particular the children," Abu Abdullah said in a YouTube plea to his colleague's captors. "Please do not take his life to pay for the crimes that the international governments have committed."
On Thursday, more than 100 British Muslim imams and organizations condemned ISIS' tactics and joined the call for Henning to be released.
The coalition of Muslim communities is appealing to ISIS and the people around them to persuade the militants to change their ways, according to Mustafa Field, Director of Faiths Forum for London, one of the signatory organizations to the petition.
"The un-Islamic fanatics are not acting as Muslims but, as the Prime Minister has said, they're acting as monsters," he told CNN. "They are perpetrating the worst crimes against humanity -- this is not jihad."
Field also had a direct message for the black-clad ISIS executioner known as "Jihadi John" -- the man with the London accent who featured in the group's gruesome videos of the beheadings of Western hostages James Foley, Steven Sotloff, and David Haines.
"John, we as Muslims are here to preserve lives," Field told CNN. "We cannot continue this barbaric action. Come back, face justice, and repent."
Those who travelled with Henning to Syria have steered clear of tough talk, adopting a softer tone in addressing the jihadists holding their friend.
"We beg you to tread the path of justice and show him the compassion in the heart of believers and in your heart," Abu Abdullah said. "We promised Alan safety and security as Muslims and ask you, the leader of Islamic State, to honor our 'amana' [bond of trust]."
Meanwhile, British Muslim community leaders have sought to distance mainstream Muslims from extremists, launching a social media campaign under the hashtag #notinmyname.
Hanif Qadir -- director of the anti-extremism charity Active Change Foundation in east London -- and local youngsters have added their voices to the anti-ISIS drive.
"Young British Muslims are sick and tired of the hate-filled propaganda the terrorists ISIS and their supporters churn out on social media," Qadir said.
"They are angry that the criminals are using the platforms to radicalise young people and spread their poisonous words of violence in the name of Islam."
Regardless of the differences in tone, everyone appealing to ISIS to free Henning agrees on one thing -- the cabbie with the heart of gold cannot be left to die.