16 know that a man is not justified by works of the law, but by faith in Jesus Christ. So we, too, have believed in Christ Jesus, that we may be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified. -Galatians 2:16 BSB
The word “justified” means that a person has been made right in God’s eyes, from being a sinner to being righteous.
The purpose of the law is to show how far we fall from God’s standard of righteousness. Only by believing and accepting what Jesus did for us on the cross and His resurrection can our sins be forgiven.
Some Jews following Jesus asked Him what works God required of them. In John 6:29, Jesus answered them like this: “Jesus replied, “The work of God is this: to believe in the One He has sent.”
With much clarity, Paul tells the Galatians, those who are going back to the law, that the only way to have our sins forgiven is by receiving Jesus’ righteousness. Jesus is the only one who lived His life on earth without sinning once and kept the whole law. The moment we put our trust in Jesus Christ, He credits us with His righteousness, and God looks at us as if we kept the whole law, even though we didn’t. If anyone thinks that someone can keep the law from childhood to one’s death, it shows a lack of biblical understanding because the moment you sin once, you have become a lawbreaker.
It also reveals that the church in Galatia was under great deception, and many were falling into Satan’s trap, see Galatians 5:2-4.
15 We who are Jews by birth and not Gentile “sinners” -Galatians 2:15 BSB
A person born in a Jewish family had a high probability of knowing and worshiping the true God, Yahweh—the Creator of heaven and earth.
6 These words I am commanding you today are to be upon your hearts. 7 And you shall teach them diligently to your children and speak of them when you sit at home and when you walk along the road, when you lie down and when you get up. 8 Tie them as reminders on your hands and bind them on your foreheads. 9 Write them on the doorposts of your houses and on your gates. -Deuteronomy 6:6-9 BSB
Gentiles, on the other hand, had a tremendous disadvantage compared to Jews because almost all of them were born into pagan families who worshiped false deities. That’s why Gentiles were called, in those times, sinners.
Paganism is the worship of idols and demons and also participating in offering their children up to their false gods in sacrificial rituals. Paganism is another way to say witchcraft. The practice of paganism continues to this day with modern terms like abortion, to give one example.
4 This issue arose because some false brothers had come in under false pretenses to spy on our freedom in Christ Jesus, in order to enslave us. -Galatians 2:4 BSB
The phrase “This issue” is about making believers go back to the Law of Moses to observe it and keep it. See verse 3 and its commentary.
What makes “some false brothers” is when they add to God’s Word, which changes it to say something other than what God said, and preaches it to others as the truth.
False teachers came to the Galatians and pretended to believe in sound teachings like salvation by grace through faith in Jesus Christ (Ephesians 2:8-9), not revealing to them that, in reality, they hold to work-based salvation. They teach that a person needs to keep the Law, which is works, plus believe in Jesus Christ to get saved. Read Galatians 3:1-2.
Paul understood that Satan is the one who influences false teachers, see 2 Corinthians 11:13-15, to enslave believers by entrapping them, teaching them to keep the Law, which makes them forsake the finished work of the cross, see Galatians 5:1-4. The cross—Jesus, who died for our sins (John 3:16, Romans 5:6-9), was to show us that our good works cannot atone for our sins and make us right in God’s eyes (Galatians 3:11). Only by accepting the gift that God offers through His Son, the Lord Jesus Christ, into our hearts by faith in Him can we have all of our sins forgiven.