When is “faith” referring to the system of faith (the Gospel) or personal faith?

Answer:

"We who are Jews by nature, and not sinners of the Gentiles, knowing that a man is not justified by the works of the law but by faith in Jesus Christ, even we have believed in Christ Jesus, that we might be justified by faith in Christ and not by the works of the law; for by the works of the law no flesh shall be justified" (Galatians 2:15-16).

This is a part of Paul's argument with Peter over the fact that Gentiles are saved equally with the Jews. Paul and Peter both knew that salvation came by faith in Jesus Christ. It was not earned by keeping the Old Law -- something no one among men had ever accomplished. Justification came from faith in Christ. "We have believed in Christ" demonstrates that Paul is discussing personal faith and not the system of faith.

"But the Scripture has confined all under sin, that the promise by faith in Jesus Christ might be given to those who believe" (Galatians 3:22).

Again the "given to those who believe" shows that the "faith in Jesus Christ" is referring to personal faith that then gives access to the promise.

"But before faith came, we were kept under guard by the law, kept for the faith which would afterward be revealed" (Galatians 3:23).

Notice the use of "the faith." Actually, in Greek both "faith"s in this verse are preceded with an article. We are speaking of a concept as an object. This is the system of faith. It arrived at a point in time after the law. So here we are talking about the system of faith -- the gospel message that replaced the older system, called "the law."

Just suppose someone were to argue that it is personal faith. Then they are claiming that every person starts out under the Old Law until some point in their life which their personal faith is revealed. This doesn't make sense in the light of the teachings of God in other passages.

"Therefore the law was our tutor to bring us to Christ, that we might be justified by faith" (Galatians 3:24).

Here the article is not present. The phrase "justified by faith" reminds us of Galatians 2:15-16, so we conclude that it is talking about personal faith.

"But after faith has come, we are no longer under a tutor" (Galatians 3:25).

Again, in Greek, there is an article before "faith." Faith is talked of arriving at a particular time, so we have moved back to talking about the system of faith, the gospel.

"But now the righteousness of God apart from the law is revealed, being witnessed by the Law and the Prophets, even the righteousness of God, through faith in Jesus Christ, to all and on all who believe. For there is no difference; for all have sinned and fall short of the glory of God, whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed, to demonstrate at the present time His righteousness, that He might be just and the justifier of the one who has faith in Jesus. Where is boasting then? It is excluded. By what law? Of works? No, but by the law of faith. Therefore we conclude that a man is justified by faith apart from the deeds of the law." (Romans 3:22-28).

"Faith" in Romans 3:22, 27, 28 are without an article. "Faith" in Romans 3:25-26 has an article. In Romans 3:22, it talks of "all who believe" and that "all have sinned," so the conclusion is that we are talking about personal faith. In Romans 3:25-26, I can see it being argued either way. The article alone is not enough to determine whether we are talking about the system of faith or personal faith. If you substitute "the Gospel" where "faith" appears and it makes perfectly good sense.

Because Romans 3:27 talks of the "law of faith" even though the article is not present, it is clear that we are talking about the system of faith, the Gospel. In Romans 3:28, we could go either way and it still makes sense.

For a detailed discussion of these verses, see Justification – Part 1.