Thomas Aquinas Commentary Galatians 3:6-9

"Even as Abraham believed God, and it was reckoned unto him for righteousness. Know therefore that they that are of faith, the same are sons of Abraham. And the scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand unto Abraham, [saying,] In thee shall all the nations be blessed. So then they that are of faith are blessed with the faithful Abraham." — Galatians 3:6-9 (ASV)

Having proved by experience the power of faith and the insufficiency of the Law, the Apostle now proves the same things by authority and reason.

The Apostle's proof has two parts:

1. He proves the power of faith to justify.
2. He proves the insufficiency of the Law (verse 10).

He proves the first point by using a syllogism, in which he does three things:

1. He proves the minor premise.
2. He proves the major premise (verse 8).
3. He draws the conclusion (verse 9).

Concerning the first of these, proving the minor premise, he does two things:

1. He proposes an authority from which he takes the minor premise.
2. He concludes the minor premise (verse 7).

He says, therefore, that justice and the Holy Spirit truly come from faith. As it is written in Genesis 15:6 and mentioned again in Romans 4:3: Abraham believed God, and it was credited to him as justice.

Here it should be noted that justice consists in paying a debt. A person is indebted to God, to themself, and to their neighbor. However, it is on account of God that they owe anything to themself and their neighbor. Therefore, the highest form of justice is to render to God what is God’s.

If you give to yourself or your neighbor what you owe but do not do this for God’s sake, you are more perverse than just, because you are making humanity your ultimate end. Everything in a person is from God—namely, the intellect, the will, and the body itself—although according to a certain order. The lower is ordered toward the higher, and external things are ordered toward internal things, for the good of the soul.

Furthermore, the highest part of a person is the mind. Therefore, the first element of justice is for a person's mind to be submitted to God, and this is done by faith: Bringing into captivity every understanding to the obedience of Christ (2 Corinthians 10:5).

Therefore, it must be said that in all things, God is the first principle of justice. Whoever gives to God the greatest thing they possess by submitting their mind to Him is fully just: Whoever are led by the Spirit of God, they are the sons of God (Romans 8:14).

And so he says, Abraham believed God—that is, he submitted his mind to God by faith. As it is written, Believe in God, and he will sustain you; direct your way and trust in him ; and further on, You who fear the Lord, believe him .

And it was credited to him as justice. This means the act of faith, and faith itself, was for him—as it is for everyone—the sufficient cause of justice. It is credited to him as justice outwardly by people, but inwardly it is worked by God, who justifies those who have faith. He does this by forgiving their sins through charity working in them.

From this authority, he draws the minor premise, saying, Therefore, know that those who are of faith are the children of Abraham. This is as if to say: Someone is called the son of another because he imitates his works. Therefore, if you are the children of Abraham, do the works of Abraham (John 8:39).

But Abraham did not seek to be justified through circumcision, but through faith. Therefore, the sons of Abraham are those who seek to be justified by faith. This is what he says: Because Abraham is just through faith, in that he believed God and it was credited to him as justice, therefore, know that those who are of faith—that is, who believe they are justified and saved by faith—are the children of Abraham by imitation and instruction.

This is confirmed elsewhere in Scripture: Those who are the children of the promise are counted as the seed (Romans 9:8); Today salvation has come to this house, because he also is a son of Abraham (Luke 19:9); and God is able from these stones to raise up children for Abraham (Matthew 3:9), by making them believers.

Then, when he says, Scripture, foreseeing that God would justify the Gentiles by faith, he presents the major premise: that Abraham was told beforehand that in his seed all nations would be blessed. When he says, Scripture, foreseeing, he introduces God speaking to Abraham (Genesis 12:3).

Therefore, he says, God told Abraham beforehand that in you—that is, in those who, like you, will be your sons by imitating your faith—all nations will be blessed. As it is also written, Many will come from the east and the west, and will sit down with Abraham, Isaac, and Jacob in the kingdom of heaven (Matthew 8:11).

Finally, when he says, Therefore, those who are of faith... will be blessed, he draws the conclusion from the premises. The argument can be formulated this way: God the Father announced to Abraham that in his seed all nations would be blessed. But those who seek to be justified by faith are the children of Abraham. Therefore, those who are of faith—that is, who seek to be justified through faith—will be blessed with the faithful, or believing, Abraham.