For several years there has been a lively debate as to whether the human Jesus did or did not exist. The link has a short but fair review of the arguments.
The no-Jesus argument seems strange to believers. There is no powerful or reliable surviving writing that talks of an actual human Jesus. What is written about Jesus is what we see in the Bible.
That Jesus was written only in the Bible and in two references sources from Bible or Christian promoters of the time does not mean Jesus did not exist. It does mean we have writing about Jesus mixed in with events that were fiction and only by subjectively deciding which was history and which fiction can one make the claim a Jesus existed.
One way some Christians handle this problem is to say Jesus was both a human and a spiritual being. By doing this the problematic arguments about him being human can be dismissed as being the spiritual Jesus. That is, no one has seen God. Jesus has not been seen except in Bible stories, neither has God. But, we know God exists so Jesus exists, goes the reasoning.
As the link author explains, it will make little difference to the believer if Jesus is proven to have existed or not. It is religion. Religion is about what people believe.
The author explains that looking for Jesus is like looking for him down a well. What you see looking back is yourself.