17
" Verse 20 is a restatement of verse 14: we need to live our lives “in line” with the truth of the gospel. Now that Christ’s life is my life, Christ’s past is my past. I am “in Christ” (v 17), which means that I am as free from condemnation before God as if I had already died and been judged, as if I had paid the debt myself. And I am as loved by God as if I had lived the life Christ lived. So “it is not me that lives, but Christ” is a triumphant reminder that, though “we ourselves are sinners”, in Christ we are righteous. Then Paul follows up with verse 21, to say: Now when I live my life and make my choices and do my work, I do so remembering who I am by faith in Christ, who loved me so much! The inner dynamic for living the Christian life is right here! Only when I see myself as completely loved and holy in Christ will I have the power to repent with joy, conquer my fears, and obey the One who did all this for me. Everything or Nothing? It’s worth remembering that Paul is still speaking to Peter here! And so he finishes by reminding Peter that the Christian life is about living in line with the gospel throughout the whole of life, for the whole of our lives. We must go on as Christians as we started as Christians. After all, if at any point and in any way “righteousness could be gained through the law, Christ died for nothing!” (v 21). Christ will do everything for you, or nothing. You cannot combine merit and grace. If justification is by the law in any way, Christ’s death is meaningless in history and meaningless to you personally. Imagine that your house were burning down but your whole family had escaped, and I said to you: Let me show you how much I love you! and ran into the house and died. What a tragic and pointless waste of a life, you would probably think. But now imagine that your house was on fire and one of your children was still in there, and I said to you: Let me show you how much I love you!, ran into the flames, and saved your child but perished myself. You would think: Look at how much that man loved us. If we could save ourselves, Christ’s death is pointless, and means nothing. If we realize we cannot save ourselves, Christ’s death will mean everything to us. And we will spend the life that He has given us in joyful service of Him, bringing our whole lives into line with the gospel. "
― Timothy J. Keller , Galatians for You (God's Word for You)
20
" Second, the gospel leads to emotional freedom. Anyone who believes that our relationship with God is based on keeping up moral behavior is on an endless treadmill of guilt and insecurity. As we know from Paul’s letters, he did not free Gentile believers from the moral imperatives of the Ten Commandments. Christians could not lie, steal, commit adultery and so on. But though not free from the moral law as a way to live, Christians are free from the it as a system of salvation. We obey not in the fear and insecurity of hoping to earn our salvation, but in the freedom and security of knowing we are already saved in Christ. We obey in the freedom of gratitude. So both the false teachers and Paul told Christians to obey the Ten Commandments, but for totally different reasons and motives. And unless your motive for obeying God’s law is the grace-gratitude motive of the gospel, you are in slavery. The gospel provides freedom, culturally and emotionally. The “other gospel” destroys both. "
― Timothy J. Keller , Galatians for You (God's Word for You)