19 For through the law I died to the law so that I might live to God.-Galatians 2:19 BSB
The Law of Moses (i.e., the Ten Commandments, animal sacrifice, circumcision, and special days) condemns everyone as no one has or can keep all of its requirements fully (see Acts 15:5-10). In James 2:10, it says, “Whoever keeps the whole law but stumbles at just one point is guilty of breaking all of it.”
Paul understands this and also knows that the only way to have a relationship with the Lord Jesus Christ is by accepting God’s righteousness through the Son of God rather than trying to keep the law—through one’s merit—to achieve righteousness, which is humanly impossible. The Law condemns but Jesus Christ is the one who justifies the person with faith.
18 If I rebuild what I have already torn down, I prove myself to be a lawbreaker.-Galatians 2:18 BSB
Paul was referring to the Law—the old covenant. He was arguing the case about what would happen if a Christian started with the grace of Jesus Christ but went back to the works of the Law.
Paul Presents His Argument Of The Consequences If One Preaches To Go Back To The Law
After preaching the gospel of grace, which is the righteousness that comes through faith in Jesus Christ since He fulfilled the law, if I [Paul or any other believer] should turn around and rebuild it again [referring to the Law] by promoting that system—keeping circumcision, dietary restrictions, the sabbath, and animal sacrifice—that righteousness comes through its adherence. I have become a transgressor of the law of Christ and have introduced another gospel, putting me [Paul] under God’s curse. See Galatians 1:8 and its commentary.
Either we accept the righteousness of Jesus Christ by placing our faith in Him and what He did for us on the cross or try to make it to heaven on our merit. We cannot hold on to both. We have to choose one.
17 But if, while we seek to be justified in Christ, we ourselves are found to be sinners, does that make Christ a minister of sin? Certainly not!-Galatians 2:17 BSB
Paul argues that people are made righteous in God’s eyes apart from the Law of Moses. Righteousness cannot come from the Law because the Law acts as a mirror, only showing the individual’s sinful condition. However, by placing our faith in Jesus and accepting what He did for us on the cross, He gives us His righteousness, while the Law, made of stone, cannot do that.
Paul asked a rhetorical question: if a person places their faith in Jesus Christ with the understanding that we are sinners and must abandon the Law to receive the righteousness that comes from faith in Christ, does that suggest Christ is leading us into sin since we are no longer under the Law? His answer is a resounding no. A person’s true conversion does not come through an outward adherence but from within, the heart, by the indwelling of the Holy Spirit.
The Judaizers (Christians who bond themselves to the Law, see Acts 15:1), at the time of Paul—who can be found even today—were teaching the churches that salvation is obtained by having faith in Jesus Christ and keeping the Law. They were probably advocating that those who have abandoned the Law for faith in Jesus alone are still living in sin, as they no longer adhere to the Law, specifically, circumcision. However, Paul makes it clear in Galatians 5:2-4 that those who want to revert to the Law are forfeiting their faith in Christ.