Answer: The Galatian saints were Gentiles by nature, but after being saved they had listened to Judaising teachers. They began simply by faith, but then sought to perfect their lives by keeping the law. This was a basic departure from the truth of the gospel, and the beloved Apostle takes them to task very sharply for having removed from the grace of Christ to another gospel, which really was no gospel at all.
Paul takes up the case of Abraham and shows that the father of the Jews, and the one in whom they boasted, was blessed unconditionally with promises from God. The law was a condition or rule of life, imposed later-four centuries later-on the Jews, to prove their helplessness to answer to God's requirements. It caused sin to become exceeding sinful; that is, what they knew to be wrong by natural conscience became a transgression when the law forbade their doing it.
It was evident then that every Jew was under the curse, for anyone who did not obey the law was cursed. How then was a Jew to be free from the curse which he incurred by failure to keep the law? Simply by believing in the Lord Jesus Christ who had so identified Himself with them that He bore the curse of the broken law in His death. So Paul can add, "Christ hath redeemed us from the curse of the law, being made a curse for us." He is speaking strictly of the Jews here, and links himself with the believing Jews in the word "us."
But is grace not to flow out to the Gentiles? for they need salvation too, although they were never under the law. Immediately, the Apostle adds, "Cursed is every one that hangeth on a tree: that the blessing of Abraham [who was blessed apart from and before the law] might come on the Gentiles through Jesus Christ." v. 14. The hanging on the tree then becomes the ground of blessing for poor Gentiles too. Then Paul concludes the point by saying, "That WE might receive the promise of the Spirit through faith." This "we" now embraces all, believing Jews and believing Gentiles.
If Christians put themselves under the law for a rule of life, or for any purpose whatsoever, they are putting themselves under the curse. And those who have the law as a rule of life, greatly lower the standard of walk, for we are identified with Christ and are to live to please Him. Those who thus walk, not only do the things which would have been required by the law, but far transcend legal requirements, and all is done as the willing service of love, not of duty.