But since Celsus rejects the statements concerning Antichrist, as it is termed, having neither read what is said of him in the book of Daniel nor in the writings of Paul, nor what the Saviour in the Gospels has predicted about his coming, we must make a few remarks upon this subject also; because, “as faces do not resemble faces,” so also neither do men's “hearts” resemble one another. It is certain, then, that there will be diversities among the hearts of men—those which are inclined to virtue not being all modelled and shaped towards it in the same or like degree; while others, through neglect of virtue, rush to the opposite extreme.
And among the latter are some in whom evil is deeply engrained, and others in whom it is less deeply rooted. Where is the absurdity, then, in holding that there exist among men, so to speak, two extremes, — the one of virtue, and the other of its opposite; so that the perfection of virtue dwells in the man who realizes the ideal given in Jesus, from whom there flowed to the human race so great a conversion, and healing, and amelioration, while the opposite extreme is in the man who embodies the notion of him that is named Antichrist?
For God, comprehending all things by means of His foreknowledge, and foreseeing what consequences would result from both of these, wished to make these known to mankind by His prophets, that those who understand their words might be familiarized with the good, and be on their guard against its opposite. It was proper, moreover, that the one of these extremes, and the best of the two, should be styled the Son of God, on account of His pre-eminence; and the other, who is diametrically opposite, be termed the son of the wicked demon, and of Satan, and of the devil.
And, in the next place, since evil is specially characterized by its diffusion, and attains its greatest height when it simulates the appearance of the good, for that reason are signs, and marvels, and lying miracles found to accompany evil, through the co-operation of its father the devil. For, far surpassing the help which these demons give to jugglers (who deceive men for the basest of purposes), is the aid which the devil himself affords in order to deceive the human race. Paul, indeed, speaks of him who is called Antichrist, describing, though with a certain reserve, both the manner, and time, and cause of his coming to the human race. And notice whether his language on this subject is not most becoming, and undeserving of being treated with even the slightest degree of ridicule.
Source: Against Celsus (New Advent)