Celsus then adds, for what reason I know not, that instead of calling Jesus the Son of God, we had better have given that honour to the Sibyl, in whose books he maintains we have interpolated many impious statements, though he does not mention what those interpolations are. He might have proved his assertion by producing some older copies which are free from the interpolations which he attributes to us; but he does not do so even to justify his statement that these passages are of an impious character.
Moreover, he again speaks of the life of Jesus as “a most infamous life,” as he has done before, not once or twice, but many times, although he does not stay to specify any of the actions of His life which he thinks most infamous. He seems to think that he may in this way make assertions without proving them, and rail against one of whom he knows nothing. Had he set himself to show what sort of infamy he found in the actions of Jesus, we should have repelled the several charges brought against Him.
Jesus did indeed meet with a most sad death; but the same might be said of Socrates, and of Anaxarchus, whom he had just mentioned, and a multitude of others. If the death of Jesus was a miserable one, was not that of the others so too? And if their death was not miserable, can it be said that the death of Jesus was? You see from this, then, that the object of Celsus is to vilify the character of Jesus; and I can only suppose that he is driven to it by some spirit akin to those whose power has been broken and vanquished by Jesus, and which now finds itself deprived of the smoke and blood on which it lived, while deceiving those who sought for God here upon earth in images, instead of looking up to the true God, the Governor of all things.
Source: Against Celsus (New Advent)