In the next place, Celsus, after referring to the enthusiasm with which men will contend unto death rather than abjure Christianity, adds strangely enough some remarks, in which he wishes to show that our doctrines are similar to those delivered by the priests at the celebration of the heathen mysteries. He says, “Just as you, good sir, believe in eternal punishments, so also do the priests who interpret and initiate into the sacred mysteries. The same punishments with which you threaten others, they threaten you.
Now it is worthy of examination, which of the two is more firmly established as true; for both parties contend with equal assurance that the truth is on their side. But if we require proofs, the priests of the heathen gods produce many that are clear and convincing, partly from wonders performed by demons, and partly from the answers given by oracles, and various other modes of divination.” He would, then, have us believe that we and the interpreters of the mysteries equally teach the doctrine of eternal punishment, and that it is a matter for inquiry on which side of the two the truth lies.
Now I should say that the truth lies with those who are able to induce their hearers to live as men who are convinced of the truth of what they have heard. But Jews and Christians have been thus affected by the doctrines they hold about what we speak of as the world to come, and the rewards of the righteous, and the punishments of the wicked. Let Celsus then, or any one who will, show us who have been moved in this way in regard to eternal punishments by the teaching of heathen priests and mystagogues.
For surely the purpose of him who brought to light this doctrine was not only to reason upon the subject of punishments, and to strike men with terror of them, but to induce those who heard the truth to strive with all their might against those sins which are the causes of punishment. And those who study the prophecies with care, and are not content with a cursory perusal of the predictions contained in them, will find them such as to convince the intelligent and sincere reader that the Spirit of God was in those men, and that with their writings there is nothing in all the works of demons, responses of oracles, or sayings of soothsayers, for one moment to be compared.
Source: Against Celsus (New Advent)