DO NOT FRUSTRATE THE GRACE OF GOD
Gal 2:17-21 But if, while we seek to be justified by Christ, we ourselves also are found sinners, is therefore Christ the minister of sin? God forbid. For if I build again the things, which I destroyed, I make myself a transgressor. For I, through the law am dead to the law, that I might live unto God. I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave Himself for me. I do not frustrate the grace of God: for if righteousness come by the law, then Christ is dead in vain.
In David's prayer to the Lord, he truthfully admits that in Thy sight shall no man living be justified (Psalm 143:2, also see Rom. 3:20). Being justified and obtaining the forgiveness of sins cannot be merited by one's own good deeds. From verses 15 and 16, preceding the lesson text, we find that the apostle Paul, who by birth was a Jew, had learned by revelation and now knew without any doubt, that a man is not justified by the works of the law, but by the faith of Jesus Christ. It was only through his obedient faith that Paul repented of his past, was baptized into the body of Christ for the remission of his sins, and found justification in the sight of God through the sin-cleansing blood of Jesus Christ.
In the lesson text, Paul confesses that while we (himself and all other Christians) seek to be justified by Christ, we ourselves also are found sinners. The explanation of this scripture seems to give many bible scholars a lot of difficulty. Without going into detail about various interpretations, it's meaning seems clear, when considered within the context in which it is written. Rereading the verses leading up to this text, we find Paul condemning false Judaizing teachers - Jews that had been converted into Christianity but were determined to bring certain Jewish laws and customs into the New Testament doctrine, which God had established through His Son, Jesus Christ. It appears that in the past, Peter, and other apostles and disciples of Christ, that were preaching New Testament Christianity to the Jewish people, had overlooked or allowed certain Mosaic laws and customs to be incorporated in the doctrine of Christ.
Compromising God's will in this fashion is sinful. Nothing is to be added to or subtracted from the New Covenant between God and mankind, that was established through His Son, and our Savior, Jesus Christ (See Rev. 22:18-19). Those that practice such, and teach others to do so, are sinners. To this Paul asks a rhetorical question: is therefore Christ the minister of sin? The obvious answer to this question is definitely, NO! If Christ condoned the pollution of God's will by false teachers, corrupting it with the rites and ceremonies of the Law of Moses, then, Paul says that Christ would be the minister of sin. Such could never be. God forbid!
Paul continues: For if I build again the things, which I destroyed, I make myself a transgressor. To abandon Christ, go back to Judaism, and teach others to do the same, Paul said would make himself a transgressor of the will of God. God's will, brought to Paul through Jesus Christ, was to preach His message of eternal salvation to the Gentiles, and kings, and the children of Israel (Acts 9:15). To teach otherwise would be a transgression in the sight of God. When God's will was revealed to Paul on the road to Damascus, he immediately obeyed what was commanded of him. It was at that point that He fully realized that justification with God, and eternal salvation, could not be found in the Mosaic Law. It was through his obedient baptism into Christ; obedience caused him to become dead to the law, and alive unto God. (A)nd the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave Himself for me.
For Paul to adulterate God's will by including Jewish rites and customs, would frustrate the grace of God. That is, it would make his teaching of the gospel of Christ null and void; to cause it to have none effect, counteract, bring confusion, and prevent it from achieving the intended effect of bringing God's message of eternal salvation, through Christ to the world. If it were possible to attain salvation through the Law of Moses, then the blood shed for the atonement of sins by the death of Christ on the cross of Calvary would have been in vain. God forbid that anyone frustrate the grace of God by compromising His word.