The question is, "So what?" A guy dies horribly, and three days later, some friends of his see him alive. 2000 years ago. "So what?"
That is the real question. The endless arguments about Jesus' existence tend to rely on either "it's not possible" or "it has to be real". What is a fact is that the New Testament is the most studied literature in history. The critical text we have today has some 25,000 complete or partial ancient manuscripts backing it. By comparison the earliest text for Julius Caesar's Gallic Wars dates around 1000 AD (copied by a monk).
It is also a fact that some of the epistles contain some eyewitness testimony, as well as parts of Mark's Gospel, at least, and maybe part of John's. Whether they are to be believed is another question, and even if we do, we are back to "so what?"
It is vital for Christians to understand that we do not believe the Bible per se, we believe the men and women in Jesus' circle. And we have to ask ourselves daily "why", and then "so what?"
My answer is, "So everything!" Others will disagree, of course. But it is ignorant to invoke sarcastic denunciations of the sources. What nonbelievers should ask is, where in your life is there any credibility to your claim that you are a follower of Jesus of Nazareth?
That is not a "so what" question at all.