Personally, the fact that the Christian leaders of the first century (especially the apostles) testify to having been his close associates should be enough. Also, the Koran speaks of him as a great prophet. As do Jewish writtings.

The only evidence that he did not exist is found in denying these religious writtings have any history in them.

I have once heard it said that, when you consider all the evidence that the United States Supreme Court would permit into a trial, the existance of Jesus, as well as his ressurection, are fact. This was stated by a lawyer (I will try to find a reference). So, the existance of Jesus of Nazereth is historical.