it pleased God, the Creator and Governor of the universe, that, since the whole body of the angels had not fallen into rebellion, the part of them which had fallen should remain in perdition eternally, and that the other part, which had in the rebellion remained steadfastly loyal, should rejoice in the sure and certain knowledge of their eternal happiness; but that, on the other hand, mankind, who constituted the remainder of the intelligent creation, having perished without exception under sin, both original and actual, and the consequent punishments, should be in part restored, and should fill up the gap which the rebellion and fall of the devils had left in the company of the angels. For this is the promise to the saints, that at the resurrection they shall be equal to the angels of God. (Luke 20:36) And thus the Jerusalem which is above, which is the mother of us all, the city of God, shall not be spoiled of any of the number of her citizens, shall perhaps reign over even a more abundant population. We do not know the number either of the saints or of the devils; but we know that the children of the holy mother who was called barren on earth shall succeed to the place of the fallen angels, and shall dwell forever in that peaceful abode from which they fell. But the number of the citizens, whether as it now is or as it shall be, is present to the thoughts of the great Creator, who calls those things which are not as though they were, (Romans 4:17) ordereth all things in measure, and number, and weight.
But this part of the human race to which God has promised pardon and a share in His eternal kingdom, can they be restored through the merit of their own works? God forbid. For what good work can a lost man perform, except so far as he has been delivered from perdition? Can they do anything by the free determination of their own will? Again I say, God forbid. For it was by the evil use of his free-will that man destroyed both it and himself. For, as a man who kills himself must, of course, be alive when he kills himself, but after he has killed himself ceases to live, and cannot restore himself to life; so, when man by his own free-will sinned, then sin being victorious over him, the freedom of his will was lost. “For of whom a man is overcome, of the same is he brought in bondage.” (2 Peter 2:19) This is the judgment of the Apostle Peter. And as it is certainly true, what kind of liberty, I ask, can the bond-slave possess, except when it pleases him to sin? For he is freely in bondage who does with pleasure the will of his master. Accordingly, he who is the servant of sin is free to sin. And hence he will not be free to do right, until, being freed from sin, he shall begin to be the servant of righteousness. And this is true liberty, for he has pleasure in the righteous deed; and it is at the same time a holy bondage, for he is obedient to the will of God. But whence comes this liberty to do right to the man who is in bondage and sold under sin, except he be redeemed by Him who has said, “If the Son shall make you free, ye shall be free indeed?” (John 8:36) And before this redemption is wrought in a man, when he is not yet free to do what is right, how can he talk of the freedom of his will and his good works, except he be inflated by that foolish pride of boasting which the apostle restrains when he says, “By grace are ye saved, through faith.” (Ephesians 2:8)
St. Augustine, Enchiridion, 29. 30