Origen summarizes Celsus' criticism of Jesus (which presumes his existence).
Origen, Contra Celsum, trans. Henry Chadwick (Cambridge: Cambridge University Press, 1953), 28
After this he represents the Jew as having a conversation with Jesus himself and refuting him on many charges, as he thinks: first, because he fabricated the story of his birth from a virgin; and he reproaches him because he came from a Jewish village and from a poor country woman who earned her living by spinning. He says that she was driven out by her husband, who was a carpenter by trade, as she was convicted of adultery. Then he says that after she had been driven out by her husband and while she was wandering about in a disgraceful way she secretly gave birth to Jesus. And he says that because he was poor he hired himself out as a workman in Egypt, and there tried his hand at certain magical powers on which the Egyptians pride themselves; he returned full of conceit because of these powers, and on account of them gave himself the title of God.
The Greek text can be found at https://archive.org/details/contracelsumlib00selwgoog/page/n44/mode/2up
Google Books preview of Chadwick's translation: https://books.google.com/books?id=BExsCHd_tUQC&newbks=0&printsec=frontcover#v=onepage&q&f=false