The birth of Christianity, nearly 2000 years ago, has shaped the whole course of human history. Yet historians still cannot explain how it all really began. What made Jesus’s followers claim to have seen him alive again, three days after his crucifixion? Why did Christianity take off so quickly?

It is one of the biggest and most profound of all historical mysteries. This extraordinary book, based on seven years of secret research by a brilliant historian, finally provides the answer. And it lies within an enigmatic relic long assumed to be a fake: the Shroud of Turin.

With historical detective work and cutting-edge scientific research, art historian Thomas de Wesselow has discovered that Jesus’s followers did see something at the tomb. They saw something real but out of the ordinary – something that seemed like a miracle. It was the burial cloth of Jesus, stained with his body image. This ancient marvel was hailed as a sign of the Resurrection, and kick-started the Christian faith.

The Sign details conclusive evidence that the Shroud of Turin is authentic, showing that the faint image on the cloth was formed naturally through a rare chemical reaction. It then explains how this revelation solves multiple puzzles of religious history: for example, the Gospel reports of the appearances of the Risen Christ are clearly based on early viewings of the Shroud.

As well as a major historical breakthrough, The Sign is a truly thrilling read – and one you will never forget.

For all press enquiries please visit The Sign Press Centre

The Sign - The Shroud of Turin and the Secret of the Resurrection

View the trailer for The Sign

How did you come to this idea?

It all startedseven years ago, after watching a TV documentary that drew attention to new evidence about the Shroudand cast doubt on the carbon-dating test. I had spent my professional life tackling art-historical puzzles, so I knew how to research it. Though initially sceptical, I soon realized it could not be a medieval fake.Then it dawned on me that it had the potential to unlock the greatmystery at the heart of Christianity.

So you think being an art historian qualifies you to write about Christian origins?

Art historians specialize in studying visual images– how and when they are made, what they mean, how they relate to texts, and so on. So, yes, I am fully qualified to write about the Shroud, which, if I am right, is at the heart of Christian belief. Only an art historian, I believe, could have seen the origin of Christianity from this point of view.

Are you religious?

Iam a committed agnostic. I am sceptical of religious claims to be in possession of revealed truth, but I nonetheless think that a forward-looking, progressive Christianity has a great deal to offer.

Does the book mean Jesus wasn't special? Don’t you think that you will upset a lot of people?

It’s definitely not my intention to upset anyone. I am not trying to ‘convert’ those who rely on their Christian faith; I am simply answering a historical puzzle. My book is not about Jesus the man, since it concerns a historical movement – Christianity – that began in the wake of his death.

What new evidence you have uncovered?

It’s a theory that can be proved and that enables us, for the first time ever, to make sense of all the evidence that has been gathered about the Shroud over the course of more than a century. I also develop new arguments and draw attention to recent findings that have been overlooked. But the key thing is to offer a new way of understanding both the Shroud and the Resurrection.

Why did you need to write in secret? And how have you managed to keep this a secret for so long?

The subject is so sensitive and controversial that I knew I had to be absolutely sure about what I was saying and make the argument complete before going public. Keeping it secret was difficult and sometimes isolating, but I knew it would be worth it in the end.

So what exactly did Mary Magdalene and the disciples see that first Easter? What was so special and why did it have such incredible repercussions?

They saw the mysterious, negative image of Jesus imprinted on his burial cloth – the Shroud. It was vanishingly faint and seemed to be a miraculous ‘spiritual body’ into which the living presence of Jesus had passed. No one had ever seen anything like it, and at that time it would have been natural to interpret it as a sign that Jesus had been raised from the dead.

So what caused the image on the cloth then?

The cause of the image has not yet been definitively established, but there is no reason to think it is anything other than a natural, if unusual, stain. The likely answer, based on rigorous scientific analysis of the image, is that it was produced by a so-called Maillard reaction, when gases from the decomposing body reacted with carbohydrate impurities on the surface of the cloth.

Why do you believe the carbon dating test in 1988 was seriously flawed? And why do you think the Catholic Church continues to refuse to allow another carbon dating test?

The agreed protocol was abandoned at the last minute at the behest of the Vatican, the sampling of the cloth was unprepared, chaotic and partially secret, and the results were presented ‘raw’, rather than being interpreted by archaeologists. I don’t know why the Vatican refuses to allow another test to be done.

There are many references in the Bible to ‘appearances’ of the Risen Jesus. How do you account for those?

The appearances of the Risen Jesus were simply viewings of the Shroud image. The first appearances are recorded as having taken place at the tomb, where the Shroud was found on Easter morning. The appearance to the Twelve occurred later that evening, when the Shroud was broughtto the upper room in Jerusalem. Subsequently,the Shroud was shown to hundreds more people, accounting for the ‘forgotten appearances’ reported by St Paul but left out of the Gospels.

The Shroud seemed to ‘disappear’ for many, many years – what happened to it?

Soon after Easter it was taken north to the Mesopotamian city of Edessa, where it was transformed into an icon – folded up and framed so that only the face was visible. This is how it was generally known until 1204, when it was looted from Constantinople. As a stolen treasure, it was kept secret for another 150 years, until a family of French knights started displaying it full-length in their local church.

How can people have confused Jesus with a mere image?

In pre-modern societies people instinctively think of images as alive, especially natural images like shadows and reflections, which are considered living doubles of the physical person. The Shroud is a natural image like a shadow or reflection, and so it, too, would have been seen as a living double, as a posthumous form of Jesus. People then had no scientific understanding of such phenomena.

How do you explain the empty tomb?

The idea of the empty tomb was a simple confusion. Over time, Christian converts who had no knowledge of the Shroud began to assume, incorrectly, that Jesus was resurrected ‘in the flesh’. So, when they repeated the tales about the women going to the tomb on Easter morning – originally tales about finding the Shroud – they added the motif of the missing body.

What could have gone wrong with the carbon-dating?

It’s possible that the sample was contaminated. This is a frequent problem with carbon- dating, and the errors can sometimes be in the region of thousands of years. Another possibility is that the sample tested was from a repair made in the Middle Ages. Unfortunately, scientists have not been given further access to the cloth, so we can’t yet decide the issue. It should be realized that archaeologists regularly reject carbon-dating results without knowing exactly what went wrong.

Why do the Gospels not mention the Shroud?

They do – it’s just a matter of recognizing it. Matthew, Mark and Luke all refer to the linen sheet in which Jesus was buried, a clear reference to the Shroud. And in the Resurrection narratives it appears as the angels seen at the tomb, dressed in white, and as the Risen Jesus himself. The Shroud is not merely mentioned in these stories: it is their focus.

Why can’t the Shroud just be a medieval painting?

For a start, scientific analysis shows that the image does not consist of paint. Then there is the fact that the image is a negative image, much like a photographic negative. No one knew about negative images until the invention of photography in the 19th century, and no one can have painted an amazingly realistic one in the Middle Ages. The image is also extremely faint, fading away completely if you get closer than about six feet, so it would have been like trying to paint an enormous canvas in invisible ink.