But observe the superficial nature of his argument respecting the former disciples of Jesus, in which he says: “In the next place, those who were his associates while alive, and who listened to his voice, and enjoyed his instructions as their teacher, on seeing him subjected to punishment and death, neither died with him, nor for him, nor were even induced to regard punishment with contempt, but denied even that they were his disciples, whereas now you die along with him.” And here he believes the sin which was committed by the disciples while they were yet beginners and imperfect, and which is recorded in the Gospels, to have been actually committed, in order that he may have matter of accusation against the Gospel; but their upright conduct after their transgression, when they behaved with courage before the Jews, and suffered countless cruelties at their hands, and at last suffered death for the doctrine of Jesus, he passes by in silence.
For he would neither hear the words of Jesus, when He predicted to Peter, “When you shall be old, you shall stretch forth your hands,” etc., to which the Scripture adds, “This spoke He, signifying by what death he should glorify God;” nor how James the brother of John— an apostle, the brother of an apostle— was slain with the sword by Herod for the doctrine of Christ; nor even the many instances of boldness displayed by Peter and the other apostles because of the Gospel, and “how they went forth from the presence of the Sanhedrin after being scourged, rejoicing that they were counted worthy to suffer shame for His name,” and so surpassing many of the instances related by the Greeks of the fortitude and courage of their philosophers.
From the very beginning, then, this was inculcated as a precept of Jesus among His hearers, which taught men to despise the life which is eagerly sought after by the multitude, but to be earnest in living the life which resembles that of God.
Source: Against Celsus (New Advent)