“Everyone is free ... to contradict me.” These words alone will make many jaws drop, for their author, who describes himself modestly as occupying “the episcopal see of Rome”, is the only writer alive today whose job definition includes the word “infallible”.

From the supposed “Rottweiler Pope” comes this gentle exposition of a simple idea: namely, that the Jesus of History and the Christ of Faith are one and the same, and that faith in Jesus Christ is reasonable.

True, he would say that, wouldn’t he? But remember the historic attitude of the Roman Catholic Church towards the academic study of the New Testament and you will see what a very remarkable book this is. The Pope’s book is, he writes, a personal search for “the face of the Lord”, rather than a formal exposition of church doctrine – but this makes its content all the more astonishing. Here we find grateful acknowledgement of the work of CK Barrett, Professor of Theology at Durham, of the Tübingen Lutheran Joachim Jeremias, and many other Protestant scholars. For a pope to write appreciatively of their works even 30 years ago would have been unthinkable. Moreover, the author accepts what the Roman Catholic Church vigorously challenged for decades: the validity of historical and critical study of the Bible.

Older Roman Catholic scholars will be wistful as they read: “I take for granted everything that...modern exegesis tells us about literary genres, about authorial intention, and about the fact that the Gospels were written in the context, and speak within the living milieu, of communities.” Any theologian who wrote those words during the pontificate of Pius X (1903-14) could easily have been branded a modernist, and excluded from a teaching office. Until the mid-20th century, any scholarly critical exegesis of the Scriptures was forbidden by Rome. Most Roman Catholic priests, until the last 20 years, would not have read the books quoted in this work for a simple reason: the pope of the day had forbidden them to do so.

The first scholars to dare investigate the historical Jesus came up with the idea, originating in Germany in the 19th century, that the Jesus of the Gospels was “not yet the Christ”. They claimed it was only later theology that made him the Christ. Ratzinger, by contrast, sets out in this book to demonstrate that the central contention of the Catholic faith – Jesus was both God and man – was told to the disciples by the Man of Nazareth himself.

There are deep problems here that Ratzinger’s book fails to address. Buried in the first three Gospels are sayings which suggest that Jesus only wanted to speak to Jews, that, for example, he regarded the Gentiles as “dogs” unfit to eat from the Master’s table. If this is an authentic saying, how can you reconcile it with the picture of Jesus telling the disciples to go and baptise and teach all nations, at the end of Matthew’s gospel? Isn’t the likeliest explanation that the saying is a bit of genuine oral tradition of the historical Jesus, who was, as many modern scholars believe, a practising Jew who had no ambition to break away from Judaism or begin a new faith for Gentiles?

On the other hand, if that is what you think, how do you account for the very early devotion, not to the memory of Jesus the prophet, but to the Living, Risen Lord? The hymn “At the name of Jesus, every knee shall bow”, first quoted in the Letter of Paul to the Philippians, almost certainly dates from 20 years or so after Jesus’s earthly life.

Nobody has ever offered a completely convincing explanation of Christian origins. Surveying the extraordinary and life-changing nature of the material in the written Gospels, the author of this book rejects the idea that it came out of the collective consciousness of a nascent church. “The anonymous community is credited with an astonishing level of theological genius – who were the great figures responsible for inventing all this?” (Did I hear a brave voice at the back answering this rhetorical question with the word “Paul”?) Another theory, the one preferred by our author, is that Jesus himself preached about his unique relationship with the father because he was what Catholicism says he is, true God and true Man.

If this book will not satisfy every puzzled reader, it will explain why the book of the Gospels is carried so reverently at Catholic and Orthodox services – half as if it were a vulnerable child, half as if it were a time bomb that might explode.

One of the best passages in the Pope’s book defines the word Gospel, the saving message, as “not just informative speech, but performative – not just the imparting of information, but action, efficacious power that enters the world to save and transform”.

For much of his argument, he relies upon the testimony of the Fourth Gospel (St John), which is written in quite a different style, and attributes to Jesus long discourses that are quite unlike the pithy sayings and stories of Matthew, Mark and Luke. Most readers of this Gospel see it as reflecting the faith of some 1st-century Christian community. This church already had the Eucharist, so there was no need here for a description of Jesus instituting the Mass at the Last Supper – as you have in Paul’s Letter to Corinth and in the other Gospels. Instead, you have a Eucharistic discourse, after the Feeding of the Five Thousand. Ratzinger writes as if it is historical: “Jesus is no myth. He is a man of flesh and blood.” The Jesus of the Fourth Gospel says, “Those who eat my flesh and drink my blood have eternal life” (John 6:54), words that the Pope says “point to what underlies the Eucharist: the sacrifice of Jesus, who sheds his blood for us”.

This would be uplifting if said in a sermon; but does it answer the simple question of the curious – is the Fourth Gospel history?

It is a great pity that this book is not finished. “As I do not know how much time or strength I am still to be given, I have decided to publish the first 10 chapters . ..” But this leaves us not only without the Pope’s treatment of the Infancy narratives – which he says he has postponed to Part II – but also, rather more crucially, without any detailed account of the arrest, trial, and death of Jesus. Until these chapters see the light of day, some of what has already been printed will seem to beg certain crucial questions. Most controversially, post Mel Gibson, the Pope gives no attention to those Jewish scholars who question the likelihood of a blasphemy trial before the Sanhedrin. (“The fact that Jesus’ trial was . . . presented to the Romans as the trial of a political Messiah reflects the pragmatism of the Sadducees” is not a sentence that answers these difficulties).

Yet there is a dogged impressiveness about the Pope’s exposition of scene after scene from the Gospel, a reading that finds it more logical to worship the Christ of Faith in the Gospels than to invent the vestiges of some Jewish prophet who had his words distorted by some later theological genius. Jesus was the genius. That is Ratzinger’s message, and the luminous intelligence of the exegesis will prompt many to respond with an Alleluia. Wordy as the old German can be, this reader at least felt that he had repeatedly identified what was haunting, indeed frightening about the Gospels. No amount of reasonable liberal “explanation” can evade the voice that comes through them – calling the reader not to a set of propositions, nor to a theory, but to a Person, who is at one with God.

JESUS OF NAZARETH: From the Baptism in the Jordan to the Transfiguration by Joseph Ratzinger, Pope Benedict XVI

Bloomsbury £14.99 pp374

Buy the book here for the offer price of £13.49 (inc p&p)

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