And besides this, one may well wonder how it happened that the disciples— if, as the calumniators of Jesus say, they did not see Him after His resurrection from the dead, and were not persuaded of His divinity— were not afraid to endure the same sufferings with their Master, and to expose themselves to danger, and to leave their native country to teach, according to the desire of Jesus, the doctrine delivered to them by Him. For I think that no one who candidly examines the facts would say that these men devoted themselves to a life of danger for the sake of the doctrine of Jesus, without profound belief which He had wrought in their minds of its truth, not only teaching them to conform to His precepts, but others also, and to conform, moreover, when manifest destruction to life impended over him who ventured to introduce these new opinions into all places and before all audiences, and who could retain as his friend no human being who adhered to the former opinions and usages.
For did not the disciples of Jesus see, when they ventured to prove not only to the Jews from their prophetic Scriptures that this is He who was spoken of by the prophets, but also to the other heathen nations, that He who was crucified yesterday or the day before underwent this death voluntarily on behalf of the human race—that this was analogous to the case of those who have died for their country in order to remove pestilence, or barrenness, or tempests? For it is probable that there is in the nature of things, for certain mysterious reasons which are difficult to be understood by the multitude, such a virtue that one just man, dying a voluntary death for the common good, might be the means of removing wicked spirits, which are the cause of plagues, or barrenness, or tempests, or similar calamities.
Let those, therefore, who would disbelieve the statement that Jesus died on the cross on behalf of men, say whether they also refuse to accept the many accounts current both among Greeks and Barbarians, of persons who have laid down their lives for the public advantage, in order to remove those evils which had fallen upon cities and countries? Or will they say that such events actually happened, but that no credit is to be attached to that account which makes this so-called man to have died to ensure the destruction of a mighty evil spirit, the ruler of evil spirits, who had held in subjection the souls of all men upon earth?
And the disciples of Jesus, seeing this and much more (which, it is probable, they learned from Jesus in private), and being filled, moreover, with a divine power (since it was no mere poetical virgin that endowed them with strength and courage, but the true wisdom and understanding of God), exerted all their efforts “to become distinguished among all men,” not only among the Argives, but among all the Greeks and Barbarians alike, and “so bear away for themselves a glorious renown.”
Source: Against Celsus (New Advent)