Why are we asking this now?

It is the oldest Bible in the world. The 4th-century book is considered to be one of the most important texts in existence. Until this week, no one alive has seen all its 800 pages together in one place because in the 19th century the document was split into sections and is now in four different locations – London, St Petersburg, Leipzig and Egypt. But the creation of an online virtual Codex Sinaiticus permits anyone to see the manuscript in its entirety at www.codexsinaiticus.org.

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Where did the Codex Sinaiticus come from?

No one is sure but it was handwritten in Greek uncial letters at about the time of the Roman emperor Constantine the Great more than 1,600 years ago. The work of four scribes, it was written on vellum parchment made from the skins of donkeys or antelopes. It was preserved for centuries by the dry desert air at the 4th century Monastery of St Catherine at the foot of Mount Sinai in Egypt, the oldest continuously inhabited Christian monastery, which has the greatest library of early manuscripts outside the Vatican City. The Codex was discovered at the monastery in 1844 by the German biblical scholar and archaeologist Constantin von Tischendorf (1815-74), who brought sections of it back to Europe on three separate trips. Von Tischendorf claimed to have found pages of it in a wastepaper basket but the monks deny this. There is a dispute too about whether he stole it or was given it. Von Tischendorf had a deed of gift dated 11 September 1868 signed by one of its archbishops. The biggest portion of the codex ended up in St Petersburg, where it was bought by the British Museum in the 1930s out of fear that the Communist regime might destroy it.

Why is the Codex so important?

To secular scholars it represents the turning point in literary history when the scroll gave way to the book. The parchment was arranged in little multi-page booklets called quires, which were then numbered in sequence. It is thought to be the oldest, large, bound book to have survived. "The Codex Sinaiticus is one of the world's greatest written treasures," says Scot McKendrick, head of Western manuscripts at the British Library. To Christian scholars, it offers key insights into which ancient religious texts were brought together in the unit we now know as the Bible. In earlier centuries there were all manner of documents in scroll form of gospels, epistles and other Christian writings. As time went by, some were judged to be authoritative and included in the canon; others were deemed to be apocryphal or errant. The Codex Sinaiticus as it survives is incomplete – originally it would have been about 1,460 pages long – but it includes half of the Old Testament, all the New Testament, and two early Christian texts not found in modern Bibles. It offers the first evidence of the content and the arrangement of the Bible, and includes numerous revisions, additions and corrections made to the text between the 4th and 12th centuries, making it one of the most corrected manuscripts in existence, showing how the text of the Bible was transmitted from generation to generation down through the ages.

Why has it never been reunited before?

Partly because the holders of the various bits were covetous of their prized pages, and partly because the pages are too delicate to be moved. So the work of digitising the pages had to be carried out in all four locations. Leaves of the Codex were first treated by conservation experts to ensure they were sufficiently stable to undergo the photographic process. Each page had to be photographed from several different angles to get a strong, readable image of the text but also to convey the natural undulation of the parchment. The result is so accurate that high-resolution digital images even show up insect bites in the skin of the animal made before the creature was slaughtered to make the vellum.

How does it differ from modern Bibles?

The version of the New Testament has some few interesting differences. It includes two works which have since been dropped from both Catholic and Protestant Bibles – "The Shepherd of Hermas", a heavily allegorical work full of visions and parables and "The Epistle of Barnabas", which contains highly-charged language about the Jews as the killers of Christ. It also includes entire books which, after the Reformation, Protestants decided to drop from their Bibles: the Old Testament books of Tobit, Judith, Wisdom, Ecclesiasticus, Baruch, Maccabbees 1&2 and large chunks of Esther and Daniel. And the running order of the books is different, reflecting subtle shifts in the priorities of the believers over the ages. The Codex omits the words which Protestants add to the end of The Lord's Prayer, and Catholics omit: "For thine is the kingdom, and the power, and the glory, for ever (Matthew 6:13).

Other differences include it saying that Jesus was "angry" as he healed a leper, where the modern text says he acted with "compassion". The story of the stoning of the adulterous woman – "Let he who is without sin cast the first stone" is not there. Nor are Christ's words about his executioners from the cross: "Father forgive them for they know not what they do". And its Gospel of Mark ends abruptly after Jesus's disciples discover his empty tomb – omitting the 12 verses on the appearance of the resurrected Christ – and leaving the disciples exiting in fear. The Codex leaves an unusual blank space where the verses should be. "That's a very odd way of ending a Gospel," says Juan Garces, the curator of the Codex Sinaiticus Project.

Does all that have any real significance?

The New Testament scholar, Bart Ehrman, has claimed the persecution of the Jews down the centuries might have been far worse had the Epistle of Barnabus remained canonical. "His blood be upon us," Barnabas has the Jews cry. But that overlooks the fact that the Gospel of Matthew contains something very similar, if not worse: "His blood be on us and on our children!" And though the Resurrection is missing from Mark, it is there in the Codex's other gospels.

Will this undermine the fundamentalists' views?

You might suppose it would upset those who believe the Bible is the inerrant, unaltered word of God, since the Codex shows there have over the centuries been thousands of alterations to today's Bible. But they can counter that there are earlier, individual manuscripts of almost all the books in the Bible; the Codex just pulls them together into a single volume. In any case, fundamentalists have long been adept at ignoring the evidence of historical biblical scholarship.

Will it change mainstream Christianity?

Scholars of the New Testament have been using this Codex for years for textual criticism, so don't expect anything very new. The creation of a virtual Codex Sinaiticus will permit the rest of us to see the manuscript as a whole as never before, but no one is expecting anything very dramatic.

p.vallely@independent.co.uk