Dan Brown’s The Da Vinci Code sold millions of copies a few years ago with a riveting subplot: the Church manipulated the biblical accounts of Jesus’ life after a few centuries. The real Jesus, writes Brown, “until that moment in history, Jesus was viewed by His followers as a mortal prophet … a great and powerful man, but a man nonetheless.”
Who was the original Jesus? How can we be sure that the Gospels were not changed over time? Worse, did Jesus even exist?
First, let’s look at what non-Christian sources have to say: is there any reference to Jesus outside of his followers’ writings, the Bible? Pliny was a Roman magistrate who was asked by Emperor Trajan in the early second century to investigate whether the Christian sect was a dangerous group. In his report to the Emperor Trajan in 110 AD, Pliny reports that Christians already believed in Jesus’ divinity: “They maintained, however, that the amount of their fault or error had been this, that it was their habit on a fixed day to assemble before daylight and to recite a form of words to Christ as god…”  Notice one important thing here: Pliny was not favorable to the Christians; he just reports what he found in his legal investigation. The historian Tacitus was another impartial record of early Christianity, who was even antagonistic to it and called Christians’ belief in Jesus a “deadly superstition.” He writes in his Annals of Imperial Rome:
Christus, from whom the name had its origin, suffered the extreme penalty during the reign of Tiberius at the hands of one of our procurators, Pontius Pilate, and a deadly superstition [the Christian faith], thus checked for the moment, again broke out not only in Judea, the first source of the evil, but also in the City [Rome]… 
These two sources, among several others, attest that Jesus existed and died more or less like the Gospels narrate, crucified at the time of Pontius Pilate, and already by the early second century Christians believed Jesus was God. To be fair, they confirm only the broad contours of the Gospels, and the question still remains: how do we know that the Gospels were not changed with time to suit the Church’s preferences and authority?
To satisfy this doubt, we need to examine the manuscripts that remain from the New Testament. Manuscripts containing at least a part of the New Testament number in the thousands, and the earliest of these date as early as the 2nd century. There are 5,800 Greek manuscripts, 10,000 Latin manuscripts and 9,300 manuscripts in various other ancient languages, including Syriac, Slavic, Ethiopic and Armenian. There is a whole science, called textual criticism, that examines these manuscripts, and contrasts the little differences between them. Princeton professor Bruce Metzger explains how each of these manuscripts is evaluated:
The more often you have copies that agree with each other, especially if they emerge from different geographical areas, the more you can cross-check them to figure out what the original document was like. The only way they’d agree would be where they went back genealogically in a family tree that represents the descent of the manuscripts. 
Textual criticism has found indeed many little variations between manuscripts, but they are almost always insignificant (like grammar and punctuation), and even the largest ones do not change any doctrine. According to scholar Bart D. Ehrman, “These scribal additions are often found in late medieval manuscripts of the New Testament, but not in the manuscripts of the earlier centuries.” In other words, this enormous body of manuscripts, agreeing with each other but in minor details, means that they must reflect the original Gospels, and that one can trace variations inserted over the centuries.
The textual reliability of the New Testament is even more impressive when contrasted to the manuscripts remaining of other works of antiquity. After the Bible, the next best preserved ancient work is Homer’s Iliad, with 650 copies originating about 1,000 years after the original copy. Caesar’s Commentaries on the Gallic War, written in the 50s BC, survives in nine copies written in the 8th century. The Jewish War by Josephus comes from nine manuscripts written in the 10th, 11th and 12th centuries. As credible as they may be, none of these ancient works comes even close to the early date and sheer number of manuscripts of the New Testament. Stephen Neills concludes that “We have a far better and more reliable text of the New Testament than of any other ancient work whatever, and the measure of uncertainty is really rather small.” The late University of Manchester scholar F. F. Bruce agreed, affirming that “the evidence for our New Testament writings is ever so much greater than the evidence for many writings of classical authors, the authenticity of which no one dreams of questioning.”
To sum up this three-post series, then: we have remarkable written evidence that the Gospels we have today are very close to the original Gospels written by Jesus’ followers; due to the historic proximity, the original writers did not have space to alter or change the eyewitness accounts of Jesus’ life significantly, and in fact include many counter-productive material that a fictional account would leave aside. The written evidence for the historical Jesus is not “thin to non-existent,” as a The Economist review of Selina O’Grady’s And Man Created God alludes, but abundant, credible, and as far as we can see, historically trustworthy.
I love fantastic accounts and conspiracy theories. In my view, this is the category that O’Grady’s revisionist account seems to fall in, while the Gospels so promptly dismissed, however, stand credible with the smell of true history.
 Letter from Pliny to Trajan, quoted Paul Barnett, Is the New Testament Reliable?, 2nd ed. (Downers Grove: IVP, 2003), 23.
 Tacitus, Annals of Imperial Rome, quoted in Barnett, 26.
 Bruce Metzger, The Canon of the New Testament: Its Origin, Development, and Significance (Oxford: Oxford University Press, 1987), 246.
 M. A. R. Habib, A History of Literary Criticism and Theory: From Plato to the Present (London: Wiley-Blackwell, 2005), 239.
 Charles Herbermann, ed., Catholic Encyclopedia. Robert Appleton Company.
 Lee Strobel, The Case for Christ: A Journalist’s Personal Investigation of the Evidence for Jesus (Grand Rapids: Zondervan, 1998).
 Stephen Neill, citato in Barnett, Is the New Testament Reliable?, 33.
 F. F. Bruce, The New Testament Documents: Are They Reliable? (Grand Rapids: Eerdmans, 2003).