Mythicism is the general position that Jesus was not a historical person but a legend and that the gospels were therefore written as a work of fiction. Much the same as William Tell, Paul Bunyan, Robin Hood and King Arthur are generally considered non-historical, mythicists argue that Jesus should added to the list. The reasons for mythicism is typically an argument from silence and the parallels to other known myths.
- There is no contemporary evidence such that Jesus existed.
- The story of Jesus resembles the stories of other generally fictional characters.
- The onus is on those individuals who claim there was a historical Jesus to back up this positive claim.
- One should not believe in a historical Jesus.
Deep investigation into the gospels casts doubt on their reliability and authenticity. The truth is we have no idea who wrote the gospels, but we can learn about their authors by examining how the texts were constructed. We find that the gospels were written by Greek-speaking, educated, rhetorically-trained writers who were skilled in Greek composition (but who never called themselves disciples) - they were not written by uneducated, illiterate, lower-class, Aramaic-speaking, disciple peasants who never went to school and who possessed no knowledge of literature.
How then did the story reach the actual educated authors? Not from the disciples, but from someone who heard the story, who heard about the story etc. They were telling stories to convert people and they improved and changed the story to fit their audiences. By the time the story reached these authors, the story had already been cast and recast through oral traditions for several decades, all of which casts serious doubt on the validity of their claims.
Many believers maintain that the gospels provide sufficient evidence for Jesus since they are supposed to have been written written by eye-witnesses during the life of Jesus. The problem with this is that none of the gospel writers met Jesus and they were written many decades after Jesus supposedly died. The earliest gospel (Mark) was probably written forty to forty-five years after Jesus died. None of the gospel's authors claim to be eye-witnesses and each gospel is written in the third-person. We have no idea who wrote the gospels or where they were written; we do not know who read them prior to the second century or if they investigated their claims in any useful way, but it is clear none of them ever met Jesus. To further support the fact that the gospel writers were not eye-witnesses we can identify large discrepancies and contradictions amongst them. Many of the gospels cannot agree on what Jesus did or said, with Mark in particular having particular problems.
There are indications that Mark may not have been a local living in Palestine, and his Gospel may have been written as a fiction. The authors Matthew and Luke got most of their info from Mark, often copying Mark verbatim. The gospels themselves are admittedly propagandist: “And many other signs truly did Jesus in the presence of the disciples, which are not written in this book: but these are written that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have through his name.” (John 20:30-31) This hardly sounds like the work of objective historical reporting.
Many parts of the gospels were added after their first version, such as the end of Mark 16, and the story of Jesus saying "let he without sin cast the first stone." There is a whole list of pieces that were later added in, and many of the books in the NT written by forgers  (all this done by early Christians). Since the gospels have been deliberately meddled with, mistranslated many times, and changed over the decades of oral traditions, there is no sound basis for trusting them as reliable historical documents. What is more problematic is that the gospels contain many events that contradict the historical record.
There is no contemporary evidence for Jesus
- Paul the Apostle (Paul of Tarsus)
- Paul never claimed to have met Jesus in person - he claimed to have received instruction from the resurrected Jesus in a vision. His conversion happened after Jesus had already died. Paul even reveals to us the earliest Christians were hallucinating on a regular basis, entering ecstatic trances, prophesying, relaying the communications of spirits, and speaking in tongues--so much, in fact, that outsiders thought they were lunatics (e.g., 1 Corinthians 14).
- How convenient that Paul should have a vision and become the new church leader, subsequently introducing many rules of his own, given that up until that point he had been working to undermine the Christian movement. However, if there was such a christian movement it does not appear anywhere in any historical account. In fact, the earliest records of jesus start with Paul, who knew very little of Jesus' life, and many statements in the letters of Paul only make sense if Paul does not view Jesus Christ as a historical person. 
- Christian apocrypha
- Stories about the stories do not qualify as historical evidence, any more than additional books about Superman prove the existence of Superman.
- There are good reasons to assume the relevant passages in Josephus are a forgery.
- In reporting on the execution of Jesus, Tacitus provides no evidence he was doing any more than echoing the story as it was told by early Christians. He does not even name Jesus. Tacitus was not himself a contemporary to Jesus, and gives no indication he drew his information from those who were.
- Suetonius: As the Jews were making constant disturbances at the instigation of Chrestus, he [Claudius] expelled them from Rome
- Chrestus is a common Jewish name, not one specially reserved for Jesus alone. Given the reference was made 20 years after Jesus is said to have died, the passage in unlikely specifically in reference to him.
- Pliny the Younger: Others named by the informer declared that they were Christians, but then denied it, asserting that they had been but had ceased to be, some three years before, others many years, some as much as twenty-five years. They all worshiped your image and the statues of the gods, and cursed Christ.
- The passage refers to Christians being annoying rather than a historical Jesus.
- Many early Christians died for their beliefs, and they wouldn't die for a lie.
- Their willingness to die shows that they believed firmly in their religious ideal, not that they believed Jesus was a real person. The religious ideal could easily have been considered a worthy cause, whether or not its founder were invented.
- If they did in fact die specifically for holding to the claim that Jesus was real (which has in no way been demonstrated), that indicates that they believed it, not that they were correct.
The story of Jesus resembles other myths
- Those stories are invented by the devil.
- A lot of parallels are stretches.
- For example Horus is said to be born of a virgin, when he was born (in one telling of the story) of Hathor and the reassembled body of Osiris.
- Joseph Campbell's Hero With a Thousand Faces showed a general outline for myths, even without the myths being inter-related. A notable amount of the argument for mythicism is that the early Christians stole the God ideas from other groups rather than invented them outright. This is not necessarily the case.
The burden is on those who argue there is a historical Jesus
- It is generally accepted that there is a historical Jesus, but this is an argument of ad populum. What really matters is what the evidence says.
- The places in the Gospels exist, however that does not give any evidence to Christ. Homer's Odyssey describes the travels of Odysseus throughout the Greek islands. The epic describes, in detail, many locations that existed in history. But should we take Odysseus, the Greek gods and goddesses, one-eyed giants and monsters as literal fact simply because the story depicts geographic locations accurately? Of course not. If in the future, archaeologists travel to the once-was New york City and discover comics off Spiderman, does that mean Spider-man was a historical person?
- Mythicism is a fringe position. Counter arguments to mythicists like this rarely go beyond ad hominem attacks.
- In the weak form — "we shouldn't believe in a historical Jesus or actively disbelieve the proposition" — it is hard to argue that a character should be accepted as due to the lack of good evidence of historicity. Keeping this in mind, it becomes progressively harder to accept a divine one if there doesn't exist the grounds for a historical one.
- Even experts have to give evidence for their beliefs, their opinions are based more on assumption and tradition than a thorough survey of the evidence.
- Nonetheless, there are still scholars that are mythicists such as theologians Robert M. Price, Thomas L. Thompson, and Tom Harpur, as well as historians Bruno Bauer, Edwin Johnson, and Bertrand Russell