Here is something most atheists and Christians can agree upon
If you haven't heard of the Jesus mythicists, they pop up in the news now and then, kind of like the the moles in Whac-a-Mole. Otherwise, they pretty much stay within their own groups and seminars, where they can practice confirmation bias unopposed.
Photo credit: Under Another Sun
Mythicists are a small minority of atheists, usually those who have strong dislike for Christianity, Christians, and Jesus, so the best way to discredit all three is for them to simply deny that Jesus existed. There's only one problem with that: most historical scholars - including atheists, Christians, agnostics, or what have you - agree that there is a very good historical case for a person named Jesus who became the basis for the Christian religion. That is not to say they all agree about his divinity, his abilities, or the accuracy off the New Testament. They do agree that the Christian religion is rooted in an actual person. One well-known scholar, Dr. Bart Ehrman, who self-identifies as agnostic, made the case for the existence of a historical Jesus in his (appropriately titled) book Did Jesus Exist?
Dr. Ehrman, who teaches at the University of North Carolina, Chapel Hill, and who at one time was an Evangelical Christian, angered some atheist mythicists and some Evangelical Christians because of his approach to the subject - mostly the kind of atheists and Christians who cannot stand to be disputed or and who cannot engage in civil discourse with people with whom they disagree. I think honest people will admit that neither Christians nor atheists own the market on intolerance or obnoxiousness.
Having studied the subject of the historical Jesus and the historical and textual evidence concerning his existence, I was glad to find Dr. Ehrman's book. As a scholar, he certainly did a better job than I ever could on a subject that tests the bounds of unbiased scholarship. Emotionally charged issues tend to do that. Nevertheless, to add my two cents and possibly alienate some Christians and atheists, I'll reproduce below my answer to What is the best evidence for a historical Jesus? as it was given on Quora:
What is the best evidence for a historical Jesus?
When it comes to ancient history, there may be no such thing as “best evidence,” particularly if you are looking for evidence in the sense of that which can be provided for recent, modern history or in the sense of the degree of probability that science can arrive at by direct observation or by reproducing the results of experiments in a laboratory. In matters of ancient history, the amount of time lapsed, the methods ancient historians and writers used to record events, and in some cases the literary practices of the ancient culture make that type of evidence almost non-existent. Historians are faced with the task of using what evidence does exist from that time period. Just verifying what authentic records and artifacts exist from a specific period of ancient history is difficult. After that, a historian must then try to determine what most likely occurred based solely on the evidence and probability, carefully filtering out bias or intuitions based on what occurred in other cultures or time periods. Amateur theorizing, apart from intricate knowledge of the various types of evidence, is not helpful.
That said, in my opinion the short, non-theological answer is this: Existing documents support the conclusion that Jesus was known as a historical person by Christian writers within twenty years of his death, and by non-Christian writers sixty to one hundred twenty years after his death. This is as close as honest scholarship can take us at this time, and from there we must draw our own conclusions. This is also the nature of ancient history, and studying the evidence for other historical figures in ancient history will confirm the difficulty of the process.
However, that does not prevent a person from trying to filter out bias, subjective theorizing, and subjective intuitions and then reasonably weighing the evidence in the light of probability. The conclusion will still be far from certain but, again, that is the nature of ancient historical studies. As this has been a subject I have pursued for some time, I will add three points to the discussion concerning the nature of evidence that can be presented for people and events from ancient history. Number two is lengthy, but necessary to the context of my answer.
First, different people have different opinions on what constitutes evidence. To me, evidence must be verifiable, which means using the best methods available to establish the evidence as credible and to determine its usefulness in evaluating the probability that a claim is true. Especially in the study of ancient history, verifiability of historical documents is an essential part of reconstructing the past, but verifying documents does not necessarily verify the people or events recorded in those documents (the authors could have been mistaken or embellishing for their own purposes).
Second, for those who do not understand the academic disciplines of philology, textual criticism, and historical criticism and how each is applied to the study of ancient writings, this is a subject on which you would do well to read the basics and read the various scholarly views on the relevant texts. I am not a philologist or textual scholar (though I did study the Koine Greek of the New Testament), and have only limited education in historical criticism, but I have studied what many scholars have written about the New Testament and historical and religious writings of that era. Intuition about how historical documents sound to our modern ears is of little value when forming opinions on the validity or authority of ancient writings. Drawing analogies to religious or mythical writings form other cultures in order to determine what did or did not happen in Palestine in that era is fanciful thinking, and this is where many who hold to the Jesus Myth theory jump off the trail of evidence to theories based on modern perceptions, not on ancient, historical and philological evidence and context. Because a myth existed in history before the time of Christ is not always proof that the myth's influence extended to Palestine. Only textual or archeological evidence can establish that link. In logic, this is the old adage that "before" does not necessarily mean "because of" when it comes to causality.
Textual criticism is an academic discipline, a branch of philology, that deals with determining as accurately as possible the original texts of ancient writings by identifying additions, transcriptions, errors, and embellishments. Like other branches of textual scholarship dealing with dates, authorship, and origins, it is applied to all manner of ancient manuscripts from the Tanakh and the New Testament to the writings of Flavius Josephus (and more recently to literary works like the Canterbury Tales and Shakespeare). Scholars examine the texts of religious, historical, philosophical, and fictional writings to determine as far as possible who the author was, the date of writing, and the original text. From there, historical criticism seeks to understand historical context of the text in order to further verify authorship and to best determine the probable meaning of the text. Both are a part of the science of philology, with philology including a greater emphasis on literary form, though the line is not hard or fast.
Considering the importance of philology, textual criticism, and historical criticism and applying them to non-Christian writings that mention Jesus, below are the ones usually mentioned, with my opinion on each.
The Testimonium Flavianum of Flavius Josephus about Jesus in Antiquities, written about sixty years after Jesus is recorded as dying, is recognized as having additions by most scholars, religious and otherwise. There is some ongoing debate about the entire passage being an insertion. From all I have read, part of the text is authentic, but additions have been made that embellish the theological status of Jesus.
Josephus also mentions James, the brother of Jesus, and this text has been called into question as an insertion by some, but not nearly as much as the Testimonium. However the text in which Josephus mentions John the Baptist is much less controversial, and all but a very few consider it authentic (See: Josephus on Jesus).
Pliny the Younger, a Roman governor, mentions Christians, but not Christ, in a letter to the Roman emperor, Trajan, in about AD 111, about 80 years after Jesus death. The reference is authentic. (See Pliny the Younger on Christians).
Tacitus, too, mentions Christians in about AD 116, and there is little debate about authenticity (See: Tacitus on Christ).
However, a larger debate surrounds the significance of these texts. In other words, does mentioning Christians or John the Baptist offer any proof that Jesus existed? No, it indicates that there were people living within one hundred years of Jesus who referred to him as a historical person.
Concerning early Christian writings about Jesus, particularly the synoptic gospels and some of the Pauline Epistles, it would be a breach of sound scholarly practice to disregard them as evidence to be considered, just as it would not be sound practice to dismiss the writings of Plato or Xenophon concerning Socrates. Everything we know of Socrates comes from the works two of his students. However, their bias is not enough to rule out the historical significance of their writings. That said, it is not the message of the gospels or Pauline Epistles that is important from a historical perspective, or what they claim about Jesus, but the fact that within twenty to forty years of the death of Jesus people believed he was a historical figure, wrote letters to others about him, and attempted to write down stories about his life and teaching. Mark is probably the earliest gospel, written about thirty or forty years after the death of Jesus, followed closely by Matthew. Luke dates within first century, and John falls at the close of the first century, AD 90-120. Perhaps more importantly, the Pauline epistles that are considered to be authentic by most scholars (Romans, I and II Corinthians, Galatians, Philippians, I Thessalonians, and Philemon) are thought to have been written within twenty to thirty years of Jesus death. In these letters you find references to events within ten years of Jesus death, and the writer considers Jesus, his brother James, Peter, and many other early associates to be real people. The mention of these events and these specific people in written correspondence to specific groups of people is historically significant, even more so than the later gospels, which were more formal records. Not surprisingly Richard Carrier and others who hold to the Jesus Myth position use all sorts of arguments to discredit these and other passages, arguments that the majority of textual critics and philologists who specialize in this area, both secular and religious, reject.
While it is true that the earliest complete copy of the New Testament dates to about 300 years after the time of Christ, there are numerous smaller fragments that attest to the fact that earlier attempts were made to write down the sayings and actions of Jesus. There have been recent claims about fragments dating earlier, but the earliest gospel fragment on which almost all scholars agree is P52, known as the Rylands Papyrus, measuring approximately 8.9 x 6 cm (3.5 x 2.5 inches), which is dated around 125 A.D. (See: St John Fragment; Rylands Library Papyrus P52).
Below: Rylands Papyrus P52, from AD 125-175, a portion of John 18:31–33, 37–38
Many more fragments of various sizes exist from 150-400 A.D. Particularly interesting are those of the synoptic gospels, which even non-Christian scholars see as indicating a connected oral and written history of early Christian teachings about Jesus. (See: List of New Testament papyri).
Papyrus 1 - a portion of Matthew 1;1-9,12,14-20, from Wikipedia
Again, this does not prove that all of the events recoded in the New Testament are true, nor does it prove Jesus was a historical person. It does indicate that in the decades following the year given as Jesus death, a group of followers began to record teachings and actions attributed to him in an attempt to establish him as bona fide prophet and the Messiah. The authors of the synoptic gospels, unidentifiable except by later tradition, wrote from thirty to ninety years after the death of Christ and were well educated and fluent in Greek. His disciples were most likely not educated in this manner, according to the accounts describing them, and excluding the remote possibility that they somehow managed to acquire this education needed to do so, or dictated the full manuscripts to someone else, the Gospel of Luke gives the best account of what these gospels represented: an attempt to write down the oral traditions of the sayings and deeds of Jesus (Luke 1:1–4). Since “miracle workers” were common at the time, as miracles supported a prophet’s claim to authority, it is not surprising that many are included, though they cannot be historically verified as having occurred. As prophets raising people from the dead was not unheard of at this place and point in history, and Jesus also was said to have raised people from the dead, the resurrection of Jesus was not as implausible in the minds of first century inhabitants of Palestine as it might be today, and would not necessarily be a deterrent in the growth of Christianity.
Is this absolute proof Jesus existed? No. It is proof that forty to sixty years after the time Jesus was said to have lived that a large following of people reportedly believed that he did exist.
Which brings me to my third point: What do you consider acceptable evidence that supports the premise that Jesus did or did not exist? As this is an emotionally charged subject, I find that many on both sides often adjust their level of evidence based on their previous bias, and then try to place the burden of proof on the other party. Granted, extraordinary claims demand extraordinary evidence, but neither textual scholars nor historians can provide the type of evidence that scientists can present by observation or experimentation concerning scientific laws that can be observed today. Philologists and historians can gather all the existing texts and then use principles of philology and textual criticism to arrive at the probability of the origins, authenticity, and content of the text. From there, they then look at the probability that the text is an accurate representation of history. That is far from certainty, but it is all historians can do for ancient writings and history.
With all of the above considered, the best evidence for a historic Jesus is in line with the evidence for other people who existed and influenced history at that time. The New Testament is one of the most copied documents of the ancient Roman world. One must consider that, from what we know of the record, Jesus was not a government official or an official leader of the Jewish people. He was an itinerant, apocalyptic preacher and teacher who proclaimed that Israel would soon be delivered from its Roman oppressors, and that it would happen in the lifetime of those to whom he spoke. Prophets and preachers with a variant of this same message were not uncommon, and some gained a following while others did not. Those who the Roman leaders felt were a threat to peace were dealt with swiftly and often harshly. Most of the people of Palestine were not literate, and those who could read and write were most often doing so for the government, including historians, or for religious purposes. Historians, scholars, and religious leaders were a tiny and select group, and wrote about only the most significant events. That Jesus is mentioned in any context is remarkable.
Still, this is not absolute proof that Jesus was a historical person. However, conclusions like author Richard Carrier presents in his book Proving History: Bayes’s Theorem and the Quest for the Historical Jesus and other deductive conclusions about the evidence are also not proof that Jesus did not exist, but theories about that evidence. Theories depend upon the fair evaluation of evidence, and evidence can be misconstrued or disregaeded by bias, particularly if the best principals of philology and textual criticism are not used to fully list all relevant data in the equation or deduction. In my opinion, the best evidence leads to the conclusion that I stated in my original short answer: Jesus was known as a historical person by non-Christian writers eighty to one hundred years after his death, and by Christian writers twenty to forty years after his death. That is as close as honest scholarship can take us at this time, and from there we must draw our own conclusions.
Added note: In my opinion, the controversy is more because of the supernatural claims the followers of Jesus made about his life, works, death, and resurrection, because these claims cannot be verified. One has to a accept them on faith. If the same secular evidence existed and only one or two religious texts about Jesus being a prophet and teacher who worked a few miracles, but the story of Jesus ended with him being simply martyred without a resurrection or subsequent claims he was God in the flesh and the only way of salvation, his existence would hardly be in question. One can question the claims made by the followers of Jesus apart from the evidence for his existence. The two issues are independent, and his existence does not validate the other claims.
My conclusion is that a man by the name of Jesus existed, and that he was probably an itinerant, apocryphal prophet and teacher, the likes of which were not uncommon at the time. That his existence, or at least the claim that he existed, evolved into a religion that has so impacted humans over the course of time is amazing to ponder, whether you are a Christian, practice a different faith or spirituality, or an atheist.
Articles and books on the non-Christian writings about Jesus:
Some scholarly works on New Testament manuscripts:
The Canon of the New Testament, Metzger, Bruce; copyright Bruce Metzger, 1987, Print Edition, Oxford Press, 2009
The Text of the New Testament in Contemporary Research: Essays on the Status Quaestionis, Volume 46, Ehrman and Michael, Editors, Copyright 1995, Wm. B. Eerdmans Publishing Co.
A Journal of Biblical Textual Criticism
The Bible: A Historical and Literary Introduction, Ehrman, Oxford University Press, 2013