Celsus criticizes the Christian belief in Jesus as the incarnation of God and attacks Christianity as a threat to the state in The True Word, or The True Discourse (now lost; known through the reply made in the third century by Origen in his Contra Celsum) written around 177. (Origen will consider it a fabricated story.)

He writes at a time when Christianity is being actively persecuted and when there seems to have been more than one emperor.

Celsus writes that Jesus's father was a Roman soldier named Panthera.

Celsus seems to have been interested in Ancient Egyptian religion, and he seems to know of Jewish logos-theology, both of which suggest The True Word was composed in Alexandria.

Celsus shows himself familiar with the story of Jewish origins.

Origen will write in 248, bringing to light again a book written in the days of Marcus Aurelius but still in circulation.

Sometimes quoting, sometimes paraphrasing, sometimes merely referring, Origen will reproduce and reply to Celsus' arguments.

Since accuracy is essential to his refutation of The True Word, most scholars agree that Origen is a reliable source for what Celsus said.