“There are two states of man without grace, as we said in Q. 109, Art. 2. One is the state of pure nature, such as was Adam before his sin. The other is the state of corrupt nature, such as is in ourselves before restoration through grace.
If we are speaking of man in the first of these states, there is one reason why he cannot merit eternal life by his natural powers alone, and that is that his merit depends on a divine preordination. No action of anything whatsoever is divinely ordained to that which exceeds what is commensurate with the power which is its principle of action. It is indeed an ordinance of divine providence that nothing shall act beyond its own power.
Now eternal life is a good which exceeds what is commensurate with created nature, since it transcends both natural knowledge and natural desire, according to 1 Cor. 2:9: 'eye hath not seen, nor ear heard, neither have entered into the heart of man…' No created nature, therefore can suffice as the principle of action which merits eternal life, unless there is added to it a supernatural gift, which we call grace. But if we are speaking of man as he exists in sin, there is a second reason why this is so, namely, the impediment of sin. Sin is an offence against God which excludes us from eternal life…
Hence no one who lives in sin can merit eternal life unless he is first reconciled to God by the remission of sin. Now sin is remitted by grace, since the sinner merits not life but death, according to Rom. 6:23: ‘the wages of sin is death.’ [Pp. 205-206 of Aquinas on Nature and Grace]”
“by the gift of grace each one of us is so moved by God that he may attain to eternal life, and eternal life cannot be merited condignly by anything other than God’s moving. But God moved the soul of Christ by grace not only that he might attain eternal life himself, but also that he might lead others to it. [Pp. 212 of Aquinas on Nature and Grace]”
Aquinas believes in a strange and mystical combination of justification by faith and works. The works are meritorious in that God does them through us, but we see that they are meritorious of salvation none the less.
This is not the Biblical doctrine of justification by faith alone that Luther so beautifully communicated. Our works have no merit... By God's grace He works through us in good works, but they don't merit salvation. Jesus propitated God's wrath on the cross [Romans 3:25; Hebrews 2:17; 1 John 2:2; 4:10]; in this act our sin was imputed to Him and His righteousness was imputed to His chosen people [2 Corinthians 5:21]; and by the gift of faith [Ephesians 2:8; Romans 3:22] man can please God again [Hebrews 11:6] and is justified in God's sight apart from works [Romans 3:27-28; Galatians 2:16].
Works play an important role in that they are the fruit of faith as James clearly teaches..."faith without works is dead," but it is not a co-foundation along with faith for salvation.
Therefore, those who teach that faith + works = salvation should take note of Romans 9:32... "Because they did not pursue it [righteousness] by faith, but as if it were based on works. They have stumbled over the stumbling stone..."
Lord, don't let us stumble...