Among the evidence they cite is the fact that, during the time he supposedly lived, there is no mention of him in any writings. For a person who was supposed to be a major rabble rouser you would think there would be at least one mention of him from the time he existed, but there is none.
Oh but there is! The contemporary historian
Josephus wrote about Jesus.
written around 9394 AD
Scholarly opinion varies on the total or partial authenticity of the reference in Book 18, Chapter 3, 3 of the Antiquities, a passage that states that Jesus the Messiah was a wise teacher who was crucified by Pilate, usually called the Testimonium Flavianum.[4][5][1] The general scholarly view is that while the Testimonium Flavianum is most likely not authentic in its entirety, it is broadly agreed upon that it originally consisted of an authentic nucleus...