As regards the second, viz. man's assent to the things which are of faith, we may observe a twofold cause, one of external inducement, such as seeing a miracle, or being persuaded by someone to embrace the faith: neither of which is a sufficient cause, since of those who see the same miracle, or who hear the same sermon, some believe, and some do not. Hence we must assert another internal cause, which moves man inwardly to assent to matters of faith.
The Pelagians held that this cause was nothing else than man's free-will: and consequently they said that the beginning of faith is from ourselves, inasmuch as, to wit, it is in our power to be ready to assent to things which are of faith, but that the consummation of faith is from God, Who proposes to us the things we have to believe. But this is false, for, since man, by assenting to matters of faith, is raised above his nature, this must needs accrue to him from some supernatural principle moving him inwardly; and this is God. Therefore faith, as regards the assent which is the chief act of faith, is from God moving man inwardly by grace.
Reply Obj. 1: Science begets and nourishes faith, by way of external persuasion afforded by science; but the chief and proper cause of faith is that which moves man inwardly to assent.
Reply Obj. 2: This argument again refers to the cause that proposes outwardly the things that are of faith, or persuades man to believe by words or deeds.
Reply Obj. 3: To believe does indeed depend on the will of the believer: but man's will needs to be prepared by God with grace, in order that he may be raised to things which are above his nature, as stated above (Q. 2, A. 3). _______________________
SECOND ARTICLE [II-II, Q. 6, Art. 2]
Whether Lifeless Faith Is a Gift of God?
Objection 1: It would seem that lifeless faith is not a gift of God.
For it is written (Deut. 32:4) that "the works of God are perfect." Now
lifeless faith is something imperfect. Therefore it is not the work of
God.
Obj. 2: Further, just as an act is said to be deformed through lacking its due form, so too is faith called lifeless (informis) when it lacks the form due to it. Now the deformed act of sin is not from God, as stated above (I-II, Q. 79, A. 2, ad 2). Therefore neither is lifeless faith from God.
Obj. 3: Further, whomsoever God heals, He heals wholly: for it is written (John 7:23): "If a man receive circumcision on the sabbath-day, that the law of Moses may not be broken; are you angry at Me because I have healed the whole man on the sabbath-day?" Now faith heals man from unbelief. Therefore whoever receives from God the gift of faith, is at the same time healed from all his sins. But this is not done except by living faith. Therefore living faith alone is a gift of God: and consequently lifeless faith is not from God.