In fact, there’s an easy formula that you can follow which is often used by Christian apologists:
Step 1: The Ad Hominem
The first step in dealing with the Jesus Mythers is to simply dismiss them. After all, the easiest way to win this argument is not to have it. Most people in our world believe that Jesus existed. The last thing Christianity needs is a discussion that makes them aware that there’s actually not one shred of evidence that dates to the time of the alleged Christ to support that conviction.
The ad hominem, where you insult your opponent instead of addressing their arguments, is very useful in this end. Casually dismiss them as crack-pots or crazy conspiracy theorists. You can throw in a false association by asking rhetorically if they also believe in the Loch Ness monster, Bigfoot or some similar mythical being. By this quip, you can help confuse who is the skeptic in the discussion and hopefully shift the burden of proof.
This tactic will probably not discourage the doubting heathen. In fact, they may object that you’re avoiding the issue by insulting them. Still, you’ve helped to set the tone of the debate and you can easily transition into step 2.
Say something along the lines of, “Oh, sorry if I sounded a bit harsh there but…”
Step 2: The Appeal to Authority
“…what else am I supposed to think of you when no historical scholar doubts the existence of Jesus?”
The appeal to authority is where you try to silence an opponent by referring to an expert or group of experts as sharing your belief. This is a logical fallacy because even experts are expected to provide evidence to support why they believe what they believe. “Because I said so” is not a logical argument even if the speaker is an expert.
The great thing about this logical fallacy is that many scholars are willing to assume the existence of a historical Jesus and leave this controversial character to the theologians. Although Christianity can’t burn heretics at the stake anymore, this multi-billion dollar industry with their millions of fanatical followers can still be a powerful and intimidating force. A professor’s career can be endangered if he or she has the temerity to question the existence of Jesus. Just ask Steve Bitterman, a community college professor in Iowa who says he was fired for questioning whether the story of Adam and Eve was just a fable. Most historians have better things to worry about than putting their careers on the line just to make a point.
Unfortunately, there are an increasing number of brave scholars like Robert Price or Acharya S. who are willing to take on Christianity. You may need to combine the “no true Scotsman” fallacy in with your appeal to authority. The “no true Scotsman” is where you make a universal generalization about a certain group of people. When a contrary example is offered, you dismiss that example as not being a “true” member of that group. In this case, you can clarify, “No serious scholar doubts the existence of Jesus.” What is a “serious scholar”? One that doesn’t doubt the existence of Jesus, of course.
If the Jesus myther persists in demanding to know the evidence that has apparently “convinced” so many scholars that Jesus existed, transition to the next step.
Step 3: The Jesus-of-the-Gaps
You may want to prepare for this step early on by downplaying just how significant Jesus was in history. If you’re forced to this step by a particularly persistent skeptic, you’ll need to be ready to admit that there is not a shred of evidence that dates to the time Jesus allegedly lived that suggests he really existed. Claim that none of this matters because it’s unreasonable to expect that such an insignificant character would be noticed by anyone at that time.
Hopefully, you won’t be debating against anyone savvy enough with the Bible to know that it alleges that Jesus was famous and had a successful ministry (Matthew 4:23-25), that he fed thousands of families with magically generated food (Mark 6:37), or that he stirred up such controversy that the Jewish leaders conspired to have him killed. To argue for an insignificant Jesus is to contradict the Gospel accounts of his life. It also precludes the possibility that he was a miracle worker, for surely the kind of miracles that Jesus allegedly performed would have gotten someone’s attention.
If your opponent makes this annoying point, you’ll need to proceed to the next step.
Step 4: Compare Jesus to Another Historical Figure
If you’re unfortunate enough to be arguing against a clever Jesus myther that has forced you to this step, you’ll need to be prepared to lie. True, this breaks one of the Ten Commandments but remember that Jesus died to fulfill these ancient Hebrew Laws, so they no longer apply. The only value the Ten Commandments have these days is to annoy freethinkers by posting them on government property. If dishonesty bothers your conscience, remember that lying for Jesus isn’t really lying; it’s committing a “pious fraud”. Feel better?
In any event, this lie involves claiming that historians believe in the existence of other historical characters even though there’s no evidence contemporary with them. Fill in whatever example you like. You’re making it up anyway.
You might, for example, claim, “There’s more evidence for Jesus than there is for George Washington”.
When evidence for Washington is offered, switch to, “There’s more evidence for Jesus than there is for Julius Caesar.”
When evidence for Caesar is produced, switch to, “There’s more evidence for Jesus than there is for Plato.”
Repeat as needed, changing the character from history as you like. Maybe you’ll get lucky and pick one that your opponent isn’t familiar with.
If your opponent insists that you stop trying to change the subject and present the evidence you have to support the idea that Jesus ever existed, proceed to the next step.
Step 5: Josephus, Pliny, et al.
Although there’s not one scrap of evidence that dates to the time Jesus allegedly lived (this point bears repeating), there are some questionable references to him that date to the end of the first century or the first half of the second. These references range from the doctored passage from Josephus’ “Antiquities of the Jews” (when Christians alter a document, make sure that you call that an “interpolation”; it sounds better than forgery) to Pliny’s letter to Trajan which confirms the existence of second century Christians (it says nothing to confirm the existence of a historical Jesus but hopefully no one will notice).
Bringing up these late references is changing the subject somewhat, since your opponent may have asked for evidence contemporary with Jesus. Don’t let this bother you anymore than the problems with each of these pieces of “historical evidence”. Remember, you’re a person of faith and faith doesn’t require you to be reasonable.
If your opponent is educated enough to know the problems with each of these references and brings you back to the subject of the dearth of evidence that is contemporary with your godman, simply retreat back to step 2 and claim that "all the scholars don't agree with you that the evidence is inadequate".
If that doesn't work, proceed to the final step.
Step 6: Wash, Rinse, Repeat
When your back is against the wall and your opponent has refuted all your arguments and now demands you to produce a shred of evidence to support idea that Jesus existed, snatch victory from the jaws of defeat by employing the most annoying of logical fallacies: Argumentum Ad Infinitum. Claim that you’ve already submitted evidence. When the skeptic points out that you haven’t, repeat your claim that you have. Go back to repeating any of the steps that we’ve already covered. Shamelessly trot out arguments that have already been shot down. Eventually, the skeptic will get tired of the repetition and give up. At this point, you “win”. Praise the sweet name of Jesus!
 "Teacher: I was Fired, said Bible isn't Literal", Megan Hawkins, Des Moines Register, Sept 22, 2007