Summa contra Gentiles3.159 Chapter CLIX. That, although man cannot be converted to God without God’s grace, yet it is reasonably im- puted to him, if he be not converted

Since, without the aid of divine grace, man cannot be directed to his last end, as we have shown in the preceding chapters; and seeing that without it man can have none of the things required that he may tend to his last end, such as faith, hope, love, and perseverance; someone might think that man is not to be blamed if he lack the things in question: and especially because man cannot merit the assistance of divine grace, nor be converted to God unless God convert him: since no one is blamed for what depends on another. But, if this be granted, it is clear that several absurdities follow. For it would follow that a man without faith, or hope, or love of God, or perseverance in good, is not deserving of punishment: whereas it is said expressly (Jo. iii. 36): He that believeth not in the Son, shall not see life, but the wrath of God abideth on him.-—And since no man obtains beatitude without these things, it would also follow that there are some who neither obtain beatitude from God, nor suffer punishment from Him. Whereas the contrary is proved from the words of Matth. xxv. 34-41, where we are told that to all who are present at God’s judgement it will be said, Come... possess the kingdom prepared for you; or Depart... into everlasting fire.

In order to clear away this doubt, we must take note that, though a man is unable, by the movement of his freewill, to merit or acquire the divine grace, nevertheless he can hinder himself from receiving it. For it is said of some (Job xxi. 14): Who have said to God: Depart from us; we desire not the knowledge of Thy ways: and (ibid. xxiv. 13): They have been rebellious to the light. And since it is in the power of the free-will, to hinder or not to hinder the reception of divine grace, he who places an obstacle in the way of his receiving grace is deservedly to be blamed. Because God, for His own part, is prepared to give grace to all, for He will have all men to be saved, and to come to the knowledge of the truth (1 Tim. ii. 4). But those alone, are deprived of grace, who place in themselves an obstacle to grace: thus he who shuts his eyes while the sun is shining is to be blamed if an accident occurs, although he is unable to see unless the sun’s light enable him to do so.