It is thus that the apostle expresses himself: “We beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto Him, that you be not soon shaken in mind, or be troubled, neither by word, nor by spirit, nor by letter as from us, as that the day of the Lord is at hand. Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition; who opposes and exalts himself above all that is called God, or that is worshipped; so that he sits in the temple of God, showing himself that he is God.
Do you not remember that, when I was yet with you, I told you these things? And now you know what withholds, that he might be revealed in his time. For the mystery of iniquity does already work: only he who now lets will let, until he be taken out of the way. And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of His mouth, and shall destroy with the brightness of His coming: even him, whose coming is after the working of Satan, with all power, and signs, and lying wonders, and with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved.
And for this cause God shall send them strong delusion, that they should believe a lie; that they all might be damned who believed not the truth, but had pleasure in unrighteousness.” To explain each particular here referred to does not belong to our present purpose. The prophecy also regarding Antichrist is stated in the book of Daniel, and is fitted to make an intelligent and candid reader admire the words as truly divine and prophetic; for in them are mentioned the things relating to the coming kingdom, beginning with the times of Daniel, and continuing to the destruction of the world.
And any one who chooses may read it. Observe, however, whether the prophecy regarding Antichrist be not as follows: “And at the latter time of their kingdom, when their sins are coming to the full, there shall arise a king, bold in countenance, and understanding riddles. And his power shall be great, and he shall destroy wonderfully, and prosper, and practise; and shall destroy mighty men, and the holy people. And the yoke of his chain shall prosper: there is craft in his hand, and he shall magnify himself in his heart, and by craft shall destroy many; and he shall stand up for the destruction of many, and shall crush them as eggs in his hand.” What is stated by Paul in the words quoted from him, where he says, “so that he sits in the temple of God, showing himself that he is God,” is in Daniel referred to in the following fashion: “And on the temple shall be the abomination of desolations, and at the end of the time an end shall be put to the desolation.” So many, out of a greater number of passages, have I thought it right to adduce, that the hearer may understand in some slight degree the meaning of holy Scripture, when it gives us information concerning the devil and Antichrist; and being satisfied with what we have quoted for this purpose, let us look at another of the charges of Celsus, and reply to it as we best may.
Source: Against Celsus (New Advent)