It was one of the most eagerly awaited scientific announcements of all time, and it pitted the world of faith against the world of rational thought, under the glare of the media. So when cutting-edge carbon-14 tests found that the Shroud of Turin was a forgery, it seemed like the final chapter for a relic that had been revered for centuries as the cloth in which Christ’s body had been wrapped when he supposedly rose from the dead at the first Easter almost 2,000 years ago.

But one man – David Rolfe, a film-maker whose documentary The Silent Witness had brought the shroud into the public eye in modern times, and who had converted to Christianity as a result of his research – wasn’t prepared to give up on it. He was convinced the carbon dating, carried out in 1988 under the direction of the British Museum and Oxford University, had been flawed. And now he claims he has the evidence to prove it. This week sees the release of a new film, Who Can He Be?, in which Rolfe argues that, far from the shroud being a definite dud, new discoveries in the past few years have again opened the question of its authenticity.

So convinced is Rolfe that he’s issuing a challenge worth $1m to the British Museum. “If … they believe the shroud is a medieval forgery, I call on them to repeat the exercise, and create something similar today,” he says. “Because from all the evidence I’ve seen, if this is a forgery it’s the most ingenious forgery in history – and of course it dates back almost 2,000 years, to a time of far less sophisticated forgery techniques.

“They said it was knocked up by a medieval conman, and I say: well, if he could do it, you must be able to do it as well. And if you can, there’s a $1m donation for your funds.”

According to the gospel accounts, it was when they discovered Christ’s burial cloth on the floor of his tomb that his followers first believed he had risen from the dead. Across the centuries, the shroud has been venerated as that very piece of fabric.

Rolfe became aware of it about 45 years ago, after he put out a request for ideas for documentaries, and the writer Ian Wilson, who had investigated the shroud – by then being kept at Turin Cathedral – got in touch. Rolfe was not a believer, but he found the history of the shroud fascinating. The documentary he went on to make won a Bafta in 1978, and brought the relic to international attention.

“My programme at no point said it was authentic, but it did pose questions, such as how did the image of the crucified man get on to the cloth, and did its provenance fit with the timeline of Christ,” says Rolfe.

The most powerful moment for him came when he took photographs of the four-metre-long shroud for the first time, and saw that the image of the dead man’s face was much more pronounced in the negatives. “It was almost as though it had been created for the photographic age,” says Rolfe.

In the mid-1980s the Vatican, the owner of the shroud, agreed in principle that it could be dated using the latest technology, and entrusted the British Museum with the task. A few years later, the verdict made headlines around the world: the cloth dated from the 13th or 14th century, and could not possibly be authentic. It seemed the relic had had its day.

But Rolfe, who is now in his early 70s, was determined to debunk the debunking. “Five [testing] protocols were agreed on, but they were all abandoned,” he says. In the glare of world publicity, the tests became a political hot potato for the British Museum. The sample used for the tests, Rolfe argues in his new film, was too small and taken from a corner where the shroud was likely to have been repaired over the centuries.

Many would argue that, even if the shroud could be proved to be the burial cloth of the man named Jesus who was crucified 2,000 years ago, that doesn’t amount to proof of his resurrection, the central tenet of Christian belief. “The carbon dating could show it was definitely from the time of Christ, but it’s still a stretch to go from that to seeing it as proof that he rose from the dead,” says Richy Thompson of Humanists UK. “Some people believe that, yes, Jesus was a real person, and we know crucifixion was a thing in those times, and Pontius Pilate is a well-documented historical figure.

“What many non-religious people would say is, where is the evidence? Because if you’re going to make extraordinary claims, you need strong evidence to back it up. And the fact that people believe [in the resurrection] is not in itself evidence that it actually happened.”

Rolfe is unperturbed: he says the image on the cloth seems to have come from a massive burst of radiation, emitted in a fraction of a second.

When it comes to the carbon dating, he’s certainly not alone in his scepticism. Barrie M Schwortz, a photographer who documented the shroud in 1978, says “murky” would be a good word to describe the events of 1988.

“Today there are at least six peer-reviewed scientific articles that challenge the results of the carbon dating,” he says. In his view, the players involved were in a hurry to get the job done, because they wanted to get carbon dating on the map. “Those tests made it a household name, and today it’s used widely in archaeology,” he says. “I’m Jewish, so I don’t have a horse in this race, but I’ve come to believe it’s the authentic burial cloth because I’ve looked at the science.”

The British Museum is less willing to get involved this time around. “Any current questions about the shroud would be best put to those who currently care for it in the royal chapel of the cathedral of Turin,” a spokesperson said.