Hello, I was curious if there were any anti-Christian authors from the ancient world (let's say 1st to 6th century) that claimed Jesus was not a historical figure. The only polemicist I know of is Celsus, but I don't think he claimed such a thing. Also, I heard something about Origen of Alexandria writing about the historicity of Jesus. I was wondering if his writing is in the context of responding to an ancient mythicist.
The problem is if there were such claims they haven't survived. Heck, there are strange gaps in what we do have. For example, Philo wrote a five volume account (c40 CE) regarding his embassy to Caligula and the events leading up to it and yet the volume that covered Pontius Pilate's rule of Judea in detail was one of the three volumes not preserved by the Christians copists. Then there are the works we only have partial rebuttals to such as Froto's Discourse against the Christians.
Grant, Michael (1995). Jesus: An Historian's Review of the Gospels. Scribner. only muddies matter as it seems to connect docetism and modern Christ Myth theory together but the section is so weirdly worded that it isn't clear what Grant's actual point was.