Any one who examines the subject will see that Jesus attempted and successfully accomplished works beyond the reach of human power. For although, from the very beginning, all things opposed the spread of His doctrine in the world, — both the princes of the times, and their chief captains and generals, and all, to speak generally, who were possessed of the smallest influence, and in addition to these, the rulers of the different cities, and the soldiers, and the people—yet it proved victorious, as being the Word of God, the nature of which is such that it cannot be hindered; and becoming more powerful than all such adversaries, it made itself master of the whole of Greece, and a considerable portion of Barbarian lands, and convened countless numbers of souls to His religion.
And although, among the multitude of converts to Christianity, the simple and ignorant necessarily outnumbered the more intelligent, as the former class always does the latter, yet Celsus, unwilling to take note of this, thinks that this philanthropic doctrine, which reaches to every soul under the sun, is vulgar, and on account of its vulgarity and its want of reasoning power, obtained a hold only over the ignorant. And yet he himself admits that it was not the simple alone who were led by the doctrine of Jesus to adopt His religion; for he acknowledges that there were among them some persons of moderate intelligence, and gentle disposition, and possessed of understanding, and capable of comprehending allegories.
Source: Against Celsus (New Advent)