Are the atheists right? Christians say "No," and there is good historical evidence for their claim. Information establishing that Jesus really lived comes to us from three categories of ancient writings: Jewish, Christian, and Roman.
Of the ancient Jewish writings, Flavius Josephus is most notable. Josephus was a historian who lived A.D. 37-97. He referred to Jesus Christ twice in his writings. In the first instance, he wrote:
Christian Sources
The most numerous references to Jesus Christ from ancient times come to us from Christian writers. The New Testament documents themselves represent this category. These twenty-seven books mention Jesus, and record some of His words and actions. Viewed as ancient literature, the New Testament books provide strong testimony to the historical reality of Jesus Christ. This is true for several reasons. First, most of the New Testament books were in circulation within forty years of Jesus' death, so the things they say about Jesus could have been challenged by those who knew the facts.
Second, some of the ancient manuscripts of these writings still in our possession date back to the second century. (In 1994, fragments of a copy of the Gospel of Matthew were determined to date back to the last quarter of the first century--an exciting discovery that is still being studied.) This space of time (between the original writings and when the copies that still exist were made) is very short when compared to most other ancient writings. For example, in the case of the writings of Aristotle, Herodotus, and Thucydides, there is a gap greater than a thousand years between the originals and the copies of their writings that have survived. Yet, no one doubts that these men lived.
Third, while a historian normally must rely upon only a handful of manuscripts for most ancient documents, New Testament scholars have thousands of manuscripts from which to work. This large number is unmatched in ancient literature. As for Herodotus and Thucydides, scholars have only eight copies of their writings to study.
Fourth, the New Testament documents give us no reason to doubt their historical accuracy. Every "checkable" fact in these books "checks out" with history. Yes, the New Testament is a proper and credible witness to the reality of Jesus Christ.
Roman Sources
Roman documents make up the third category of ancient sources testifying that Jesus really lived. Before considering examples from this group, however, it is important to note why we should not expect to find many references to Jesus in Roman sources. Imagine you are a preacher for a small country congregation in Oklahoma. If you stayed there for three years, how often do you suppose your name would appear in the Washington Post or the New York Times? That is more in keeping with the level of expectation we should have when it comes to reading about Jesus in ancient Roman writings. An obscure carpenter with few friends, from a remote town thousands of miles from Rome, would hardly make front-page news in the capital city of the world! Even His death on the cross was commonplace in that age of extreme cruelty. Nonetheless, some references were made to Jesus.
Three authors stand out. First, Suetonius (an author who wrote biographies of the first twelve Roman emperors) referred to Christ and Christians in A.D. 120. Second, Pliny the Younger, a governor of Bithinia, sent a letter to the Emperor Trajan in A.D. 112 asking for advice on what to do with Christians. Among other things, he wrote that they "were in the habit of meeting on a certain fixed day before it was light, when they sang in alternate verses a hymn to Christ, as to a god...." [quoted in The Verdict of History: Conclusive Evidence for the Life of Jesus by Gary Habermas (Nashville: Nelson, 1988), p 95)]
Third, perhaps the most outstanding Roman writer who mentioned Jesus was the historian Cornelius Tacitus. In his Annals, written about A.D. 116, Tacitus said this about Nero's attempts to avoid being blamed for the burning of Rome: