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.