There are considerable reports from non-Christian sources that supplement and confirm the Gospel accounts. These largely come from Greek, Roman, Jewish and Samaritan sources of the first century. They include Tacitus (a first-century Roman who is considered one of the more accurate historians of the ancient world); Pliny the Younger (a Roman author and administrator); Lucian of Samosata (a second-century Greek writer), and Josephus, who was a Pharisee of the priestly line and a Jewish historian, though he worked under Roman authority.
These various historical sources show widespread agreement about the basic details of Jesus’ life, especially His death and its causes, with some consideration given to the belief that he rose from the dead.
In his book, The Verdict of History, Gary Habermas details a total of thirty-nine ancient sources documenting the life of Jesus, from which he enumerates more than one hundred reported facts concerning Jesus’ life, teachings, crucifixion, and resurrection. (1) What’s more, twenty-four of the sources cited by Habermas, including seven secular sources and several of the earliest creeds of the church, specifically concern the divine nature of Jesus.
Thirty nine sources may not seem like a much attestation. However, you cannot expect to find much 1st century writings, outside the Gospels, referring to Jesus. The fact is, not much about anything of that day has survived to the present time. What did survive indicates the writers of that time would not have been interested religious events that did not directly concern them.
A reading of works of some of the 1st century historians reveals very quickly that they concerned themselves almost completely with the major political and international events of the day. When it came to religious events, only those which had bearing on the “more important” national and international affairs were mentioned. (1)
An incontrovertible reference to Jesus would have to be from an eyewitness. But outside of Christian testimony, no surviving historical literature could even be expected to contain eyewitness references to Him. So the modern historian must seek non-Christian evidence for Jesus the same way he does for every other person of antiquity who was considered insignificant by the authorities of his day. He must analyze the credibility of secondhand
reports. (2)
If you combine the secondhand reports of Jesus (both non-Christian and Christian) with the eyewitness accounts recorded in the Gospels, you will find that Jesus compares extremely favorably with other people in history whose historicity is not in doubt. Concerning Jesus, Gary Habermas, professor of Philosophy and Religion at Liberty University states: