Contra Celsum

Against Celsus (Greek Κατὰ Κέλσου, Kata Kelsou; Latin Contra Celsum), is the title of a major work by the Church Father Origen of Alexandria, written in 248 AD, countering the writings of Celsus, a pagan philosopher and controversialist who wrote a scathing attack on Christianity in his treatise The True Word.

...
Wikipedia