The first-century historian Josephus reports that Jesus was a sage who performed wonders. This is a non-Christian source from Jesus’s era. This is treated briefly in the following video:
https://www.youtube.com/watch?v=zGxRQDXq-o0
Some internet detractors demand eyewitness reports from the first century before they will believe, but such a demand displays historiographic ignorance–by this standard we would know almost nothing about ancient history. We have the next-best thing: sources from the first generation, including some who consulted eyewitnesses (Luke 1:1-2). I have addressed these issues elsewhere (including in http://www.craigkeener.org/gospel-truth-luke-11-4/; http://www.craigkeener.org/the-real-historical-jesus/; for videos: http://www.craigkeener.org/gospels-as-ancient-biographies-part-1/; http://www.craigkeener.org/gospels-as-ancient-biographies-part-2/; http://www.craigkeener.org/can-we-trust-the-disciples-to-have-remembered-jesus-teachings-correctly/), but suffice it to say that unless critics invent special standards for Jesus that we do not apply to the rest of ancient history, we know quite a lot about him. (As for eyewitness testimonies of miracles, we not only have sources from within a generation of Jesus’s ministry, but we do have eyewitness accounts of his followers performing miracles, such as in Acts’ “we” section, Paul’s appeal to the Corinthians’ eyewitness experience of his miracles, eyewitness accounts in the church fathers, and millions of eyewitness claims today. But that is, again, another story. See e.g., http://www.craigkeener.org/divine-action-presentation-at-oxford-video/; http://www.craigkeener.org/medical-evidence-of-miracles/; and other material filed at http://www.craigkeener.org/category/current-issues/miracles/)
