No original text of the Bible (autograph) remains, what we have is copies of copies of copies, so how can we be certain that the copying was carried out without error? As far as the Old Testament is concerned, the process of copying was entirely in the hands of the Hebrew scribes and they went to extraordinary lengths to make sure errors did not occur.

The following description is given by Scott Manning at: scottmanning.com/archives/scribeswritingoldtestament.php.

In 586 B.C., Jerusalem was captured by the Babylonians. The Temple was looted and then destroyed by fire. The Jews were exiled.

About 70 years later, the Jewish captives returned to Jerusalem from Babylon. According to the Bible, Ezra recovered a copy of the Torah (Genesis, Exodus, Leviticus, Numbers, and Deuteronomy) and read it aloud to the whole nation.

From then on, the Jewish scribes solidified the following process for creating copies of the Torah and eventually other books in the Old Testament.

1. They could only use clean animal skins, both to write on, and even to bind manuscripts.
2. Each column of writing could have no less than forty-eight, and no more than sixty lines.
3. The ink must be black, and of a special recipe.
4. They must verbalize each word aloud while they were writing.
5. They must wipe the pen and wash their entire bodies before writing the word “Jehovah,” every time they wrote it.
6. There must be a review within thirty days, and if as many as three pages required corrections, the entire manuscript had to be redone.
7. The letters, words, and paragraphs had to be counted, and the document became invalid if two letters touched each other. The middle paragraph, word and letter must correspond to those of the original document.
8. The documents could be stored only in sacred places (synagogues, etc).
9. As no document containing God’s Word could be destroyed, they were stored, or buried, in a genizah – a Hebrew term meaning “hiding place.” These were usually kept in a synagogue or sometimes in a Jewish cemetery.

The final item is why we have no original manuscripts of the Old Testament today.

After Jerusalem was sacked by Rome in the First Century, the process was lost. While a Hebrew version of the Old Testament continued to exist, the language wasn’t spoken by many. Greek and eventually Latin versions continued to be copied.
How Accurate Were the Scribes?

Beginning in the Sixth Century and into the Tenth Century A.D., some European Jewish scribes continued a similar method for copying manuscripts of the Old Testament in the original Hebrew language as originated by the scribes before Christ.

Until 1948, the oldest manuscripts of the Old Testament dated back to AD 895. In 1947, a shepherd boy discovered some scrolls inside a cave west of the Dead Sea. These manuscripts dated between 100 B.C. and 100 A.D. Over the next decade, more scrolls were found in caves and the discovery became known as the Dead Sea Scrolls. Every book in the Old Testament was represented in this discovery except Esther. Numerous copies of each book were discovered (For example, 25 copies of Deuteronomy).

A comparison of the two lots of documents, even though they are almost 1,000 years apart, show very few discrepancies and this gives a good indication to the diligence of these scribes with respect to their copying accuracy.
The New Testament

The same precise procedures were not followed by those who copied the books of the New Testament, but the difference here is the great profusion of copies; approximately 5,500 of Greek complete or partial copies alone. However they are a lot closer to the autographs than those of the Old Testament.

What ancient documents have survived and what does this tells us?

The oldest surviving NT scripture dated to around AD 125, is a fragment of John’s gospel, on one side is a small portion of 18:31-33 in which Pilate asks the famous question; What is truth? And on the reverse, are from verses 37-38 in which Jesus replies; Everyone who is of the truth hears my voice. It has become known as the John Ryland fragment or P⁵² since it is housed in the John Ryland Library, Manchester, England.

The Bodmer Papyri are a group of twenty-two papyri discovered in Egypt in 1952. They are named after Martin Bodmer who purchased them. The papyri contain segments from the Old and New Testaments, early Christian literature, Homer and Menander. The oldest, P⁶⁶ dates to between 175 and 200 and contains the first 15 chapters of John’s gospel.

The most important New Testament documents to date, are a group called the Chester Beatty Papyri. They consist of twelve codices (books) containing most of the books of the New Testament dating from possibly the early 100s to about 300.

Codex Sinaiticus is one of the most important books in the world. Handwritten well over 1600 years ago on parchment in uncial letters, the manuscript contains the Bible in Greek, including the oldest complete copy of the New Testament. Its heavily corrected text is of outstanding importance for the history of the Bible and the manuscript – the oldest substantial book to survive Antiquity – is of supreme importance. It has been dated to early 300s.

The Codex Vaticanus, this Codex is named after its place of conservation in the Vatican Library, where it has been kept since at least the 15th century. It is written on 759 leaves of parchment (vellum) in uncial letters and has been dated palaeographically to between 325 and 350. It contains most of the Old Testament and the New Testament, but unfortunately the smaller books of 1 and 2 Timothy, Titus and The Revelation are missing.

The other codex of the group that has been termed; the big three (Sinaiticus, Vaticanus and Alexandrius), is the Codex Alexandrinus. It was written later than the other two and sometime in the 400s.

The historical veracity of the New Testament writings compare well with other historical documents that people have no trouble believing, as shown in the table below.

Author                                    Date Written                       Earliest Manuscript                     Time Span                     Number of Manuscripts

Caesar                                            100-44 BC                                      AD 900                                          1,000 years                                     10

Plato                                               427-347 BC                                     AD 900                                         1,200 years                                       7

Thucydides                                   460-400 BC                                    AD 900                                         1,300 years                                       8

Tacitus                                          AD 100                                            AD 1,100                                       1,000 years                                     20

Suetonius                                     AD 75-160                                      AD 950                                              800 years                                       8

Homer (Iliad)                             900 BC                                             400 BC                                              500 years                                   643

New Testament                         AD 40-100                                       AD 125                                          25-50 years                             >24,000

*Source of table: J. Sarfati, Creation, 2011, 33(1), page 33

References

Comfort, Philip Wesley (1991). The complete guide to Bible versions. Wheaton, IL: Tyndale House Publishers. pp. 16-20.

Connolly, W. Kenneth (1996). The indestructible book: the Bible, its translators, and their sacrifices. Grand Rapids, MI: Baker Books. pp. 17-18.