It was standing room only for the emotional Charlie Hebdo press conference on Tuesday afternoon, as the surviving members of the team vowed that the magazine would continue and its spirit would not be broken.

In the packed cafe area at the top of Libération’s offices, where the surviving members of Charlie Hebdo have been working since Friday, editor-in-chief Gérard Biard held up the new edition of the magazine, which features a picture of the prophet Muhammad crying below the words “All is forgiven”. Biard said the edition had been made “with joy as well as pain”.

“We are happy to have done it, happy to have managed to do it,” he said. “It was difficult because it had to be something of us, something of the events which we have been confronted with. This edition – the whole of Charlie Hebdo is in it. This edition is Charlie Hebdo.”

He thanked the institutions and individuals who had pledged their support and money to the magazine following the attack on its offices last Wednesday that left 12 people dead, including two police officers. “There will be a future, there is no doubt about that,” he said. “We don’t know what it will look like yet, but there will be a magazine, there will be no interruption.”

And, this being a Charlie Hebdo press conference, there had to be some humour, despite the tears held back by cartoonist Luz – who drew the front page – and columnist and doctor Patrick Pelloux, who sat next to Biard.

“Thank you for being here,” said the editor-in-chief, who was on holiday when the attack happened. “I’d like to say thank you for this moment, but that one is already taken,” he joked, referring to the recent memoir, Merci Pour Ce Moment, by the French president’s former partner Valérie Trierweiler.

Luz told the world’s assembled media, who were packed into every inch of space in the makeshift conference room, that he had no fear after drawing the picture of Muhammad on the front cover of the magazine. “I have no worries about the cover,” he said. “We have confidence in people’s intelligence and we have confidence in humour. The people who did this attack, they have no sense of humour.”

Luz added: “I’m sorry we’ve drawn him yet again but the Muhammad we’ve drawn is a man who is crying.”

In a deeply personal testimony, the cartoonist, clearly struggling with emotion, explained that after the attacks the team had been forced to go back to work. “I was in a corner, I summoned all the talent of those who weren’t there and all those who were. We said: ‘We have to have a drawing that makes people laugh’.”

On his moment of inspiration, he added: “There was this idea to draw this character [...] I looked, he was crying; then I wrote “all is forgiven”, then I cried. It was the front cover. It wasn’t the one that the world wanted us to do, or the terrorists, but it was ours.”

Charlie Hebdo will come out on Wednesday, with a print run of 3m, instead of the usual 60,000 copies.

Biard called the front cover “astounding”. “When we saw it we all burst out laughing and threw ourselves into each other’s arms,” he said.

An editorial written by Biard says Charlie Hebdo, which it describes as an atheist publication, “has accomplished more miracles than all the saints and prophets put together”.

“What we are most proud of is what you have in your hands, the magazine that we have always produced, in the company of those who have always produced it,” the editorial reads. “What made us most laugh is that the bells of Notre-Dame rang in our honour.”

Biard adds that the magazine has felt “a little alone” in the last few years and he makes an impassioned plea for everyone who used the phrase “Je suis Charlie” over the past few days to defend secularity now. “We will hope that as of 7 January 2015, the strong defence of secularity will be obvious to everyone,” he writes, adding that “cultural relativism [...] opens the way to only one thing: religious totalitarianism.”

Digital versions of the magazine will be available in Spanish, Arabic, French and English, while the Turkish daily Cumhuriyet and the Italian Il Fatto Quotidiano will be the only publications to publish the print edition in their own pages. Biard said the team especially wanted to publish the Turkish publication, because laïcité – the separation of religion and state – was under threat there too.

He urged people to go to newspaper stands to buy the edition. “Go and buy it,” he said. “If we can make [Charlie Hebdo] live, we can make ideas live in France and throughout the world – then we really will have won.”

Charlie Hebdo staff working at the offices of Liberation following the deadly attack. Photograph: Bertrand Guay/AFP/Getty Images

How the edition was produced

In the hours following the bloody attack, the idea that the magazine could come out a week later seemed impossible. Its editor, Stéphane Charbonnier, known as Charb, was dead, as were nine key cartoonists, contributors and subeditors, as well as a visitor to the offices. But the reaction of the surviving members – and their compatriots – was immediate. Offers of help and funds flooded in from media organisations, individuals and companies around the world, while cartoonists offered drawings for free and donations to keep the team going.

By Friday, the remaining team had set up camp at Libération, where they had taken refuge in 2011 after Charlie Hebdo’s offices were firebombed following the publication of cartoons depicting the prophet Muhammad.

“When they came up the stairs it was like a funeral procession,” said Lawrence Defranoux, online editor of international news at the newspaper.

“Our papers are close, we share some contributors, so they stopped to say hello to those they knew, but there were already so many demands for interviews that they quickly put up a screen and a note.”

The note was still there on Tuesday as journalists arrived for the press conference. It read: “No journalists”, with a small note below adding: “Thank you”. Having already lost two days’ work, and with a skeleton team, the core group of about 25 people entered Libé’s “porthole” conference room, where the paper holds its morning editorial meeting. With five police officers standing guard outside the room, and more on the street below where the iron shutters had been closed since Wednesday, a delivery of computers was accepted on loan from Le Monde, the heating was turned up and the windows were opened to let the team smoke.

With swollen eyes, those who would create the new edition went to work: among them Luz, Willem, Coco, Babouse, Sigolène Vinson, Antonio Fischetti, Zineb El Rhazoui, Laurent Léger.

At that first meeting, they discussed how the pages would be filled? “Right, shall we make the paper?” asked editor-in-chief Gérard Biard. The answer came quickly, in the true Charlie Hebdo style: “I don’t know what’s going on in the news,” said Patrick Pelloux, the doctor and columnist who arrived at the paper’s offices just moments after the massacre had taken place, and tried desperately to save the lives of his friends.

Biard put forward his opinion. “I would be in favour of making a ‘normal’ edition. So that readers recognise Charlie. So that it’s not even a special edition,” he said, according to Libération media journalist Isabelle Hanne, who was given special access to the team. “Not bad,” was the reply from the table.