1 In the previous books I have set forth the causes for which God permitted these things to be made, and have pointed out that all such have been created for the benefit of that human nature which is saved, ripening for immortality that which is [possessed] of its own free will and its own power, and preparing and rendering it more adapted for eternal subjection to God. And therefore the creation is suited to [the wants of] man; for man was not made for its sake, but creation for the sake of man. Those nations however, who did not of themselves raise up their eyes unto heaven, nor returned thanks to their Maker, nor wished to behold the light of truth, but who were like blind mice concealed in the depths of ignorance, the word justly reckons “as waste water from a sink, and as the turning-weight of a balance— in fact, as nothing;” so far useful and serviceable to the just, as stubble conduces towards the growth of the wheat, and its straw, by means of combustion, serves for working gold. And therefore, when in the end the Church shall be suddenly caught up from this, it is said, “There shall be tribulation such as has not been since the beginning, neither shall be.” For this is the last contest of the righteous, in which, when they overcome they are crowned with incorruption.
2. And there is therefore in this beast, when he comes, a recapitulation made of all sorts of iniquity and of every deceit, in order that all apostate power, flowing into and being shut up in him, may be sent into the furnace of fire. Fittingly, therefore, shall his name possess the number six hundred and sixty-six, since he sums up in his own person all the commixture of wickedness which took place previous to the deluge, due to the apostasy of the angels. For Noah was six hundred years old when the deluge came upon the earth, sweeping away the rebellious world, for the sake of that most infamous generation which lived in the times of Noah. And [Antichrist] also sums up every error of devised idols since the flood, together with the slaying of the prophets and the cutting off of the just. For that image which was set up by Nebuchadnezzar had indeed a height of sixty cubits, while the breadth was six cubits; on account of which Ananias, Azarias, and Misaël, when they did not worship it, were cast into a furnace of fire, pointing out prophetically, by what happened to them, the wrath against the righteous which shall arise towards the [time of the] end. For that image, taken as a whole, was a prefiguring of this man's coming, decreeing that he should undoubtedly himself alone be worshipped by all men. Thus, then, the six hundred years of Noah, in whose time the deluge occurred because of the apostasy, and the number of the cubits of the image for which these just men were sent into the fiery furnace, do indicate the number of the name of that man in whom is concentrated the whole apostasy of six thousand years, and unrighteousness, and wickedness, and false prophecy, and deception; for which things' sake a cataclysm of fire shall also come [upon the earth].
Source: Adversus haereses (New Advent)