Important historical evidence comes from the pen of the Roman historian Tacitus (c. 56—120). He was a careful scholar, so his brief reference to the historical Jesus is very important. His collection of books called The Annals includes the famous story about the six-day fire, that burned much of Rome in July AD 64 and was set by Emperor Nero himself. To put that rumor to rest, Nero blamed Christians for setting the fire. Tacitus describes the support for the homeless provided by Nero and the rebuilding of the city. However, none of this did away with the suspicion that the fire had been started on Nero's orders:

Consequently, to get rid of the report, Nero fastened the guilt and inflicted the most exquisite punishments on a class hated for their disgraceful acts, called Chrestians by the populace. Christ, 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 Pilatus, and a most mischievous superstition, thus checked for the moment, again broke out not only in Judaea, the first source of the evil, but even in Rome, where all things hideous and shameful from every part of the world find their centre and become popular. Accordingly, an arrest was first made of all who pleaded guilty; then, upon their information, an immense multitude was convicted, not so much of the crime of firing the city, as of hatred against mankind. Mockery of every sort was added to their deaths. Covered with the skins of beasts, they were torn by dogs and perished, or were nailed to crosses, or were doomed to the flames and burnt, to serve as a nightly illumination, when daylight had expired.

Tacitus then returns to the topic of Nero's reputation and the effect on it of these events:

Nero offered his gardens for the spectacle, and was exhibiting a show in the circus, while he mingled with the people in the dress of a charioteer or stood aloft on a car. Hence, even for criminals who deserved extreme and exemplary punishment, there arose a feeling of compassion; for it was not, as it seemed, for the public good, but to glut one man's cruelty, that they were being destroyed.

Tacitus misspelled Christian in the passage, but he reported that the error was a mistake of the crowd that he then corrected when he mentioned “Christ.” The fact that he calls Jesus, "Christ" doesn't imply any belief that Jesus is the Messiah. It probably just reflects how Christians were referring to Jesus at that time. His reference that Jesus was executed doesn't refer specifically to crucifixion, but the fact that some Christians were crucified indicates that Nero was aware of the tradition.

Finally, Tacitus confirms the canonical gospel portrait that Pilate executed Jesus as an enemy of Rome. There is nothing mentioned about any Jewish involvement in the Crucifixion.

The surviving copies of Tacitus' works derive from two principal manuscripts, known as the Medicean manuscripts, which are held in the Laurentian Library, and written in Latin. It is the second Medicean manuscript which is the oldest surviving copy of the passage describing Christians. In this manuscript, the first 'i' of the Christianos is quite distinct in appearance from the second, looking somewhat smudged, and lacking the long tail of the second 'i'; additionally, there is a large gap between the first 'i' and the subsequent long s. Georg Andresen was one of the first to comment on the appearance of the first 'i' and subsequent gap, suggesting in 1902 that the text had been altered, and an 'e' had originally been in the text, rather than this 'i'.

In 1950, at Harald Fuchs' request, Dr. Teresa Lodi, the director of the Laurentian Library, examined the features of this item of the manuscript; she concluded that there are still signs of an 'e' being erased, by removal of the upper and lower horizontal portions, and distortion of the remainder into an 'i'. In 2008, Dr. Ida Giovanna Rao, the new head of the Laurentian Library's manuscript office, repeated Lodi's study, and concluded that it is likely that the 'i' is a correction of some earlier character (like an e), the change being made an extremely subtle one. Later the same year, it was discovered that under ultraviolet light, an 'e' is clearly visible in the space, meaning that the passage must originally have referred to chr'estianos, a Latinized Greek word which could be interpreted as the good, after the Greek word ??????? (chrestos), meaning 'good, useful'.

According to Professor Robert Renehan, it was "natural for a Roman to interpret the words [Christus and Christianus] as the similarly-sounding ???????". Some early Greek scribes apparently had a similar issue, for the word for "Christians" is ??????????? in Acts of the Apostles 11:26 according to both Codex Sinaiticus and in Minuscule 81.

Annals 15.44 in history

Early Christian writers such as Tertullian, Lactantius, Sulpicius Severus, Eusebius and Augustine of Hippo do not refer to Tacitus when discussing the subject of the Christian persecution by Nero. Furthermore writer, Suetonius, mentions Christians being harmed during this period by Nero, but there is no connection made with the fire.

Those critical of the passage's authenticity argue that early Christian writers likely would have sought to establish the historicity of Jesus via secular or non-Christian documents, and that their silence with regard to the Annals in this manner may suggest that the passage did not exist in early manuscripts. Furthermore, because the earliest surviving manuscript containing the passage is an 11th century Christian scribal copy, skeptics of the passage's authenticity argue that it may be the result of later Christian editing.

Supporters of the passage's authenticity, however, counter that Christians would not promote their faith as a "most mischievous superstition", or a "source of the evil" or as something "hideous and shameful", though "there arose a feeling of compassion" toward the Christians. The criterion of embarrassment suggests authenticity, and there is no historical or archaeological evidence to support the argument that a scribe may have introduced the passage into the text.

The rank of Pilate

Pilate's rank while he was in Judea appeared in an inscription which called him a prefect, while this Tacitean passage calls him a procurator (Latin). Josephus refers to him with the generic Greek term ??????, or governor. Van Voorst thinks that the use such different terms is what one would expect from witnesses writing in different languages, at different times in history.

Tacitus records that Claudius was the ruler who gave procurators governing power. After Herod Agrippa's death in AD 44, when Judea reverted to direct Roman rule, Claudius gave procurators control over Judea.

Summary

The passage contains an early non-Christian reference to the origin of Christianity, the execution of Christ described in the Bible's New Testament gospels, and the presence and persecution of Christians in 1st-century Rome. While a majority of scholars consider the passage authentic, some scholars have argued that it may not be authentic.