For all who rely on works of the law are under a curse; for it is written, “Cursed be everyone who does not abide by all things written in the Book of the Law, and do them.” Now it is evident that no one is justified before God by the law, for “The righteous shall live by faith.” But the law is not of faith, rather “The one who does them shall live by them.” Christ redeemed us from the curse of the law by becoming a curse for us—for it is written, “Cursed is everyone who is hanged on a tree”— so that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit through faith.
This seems to be a continuation of the previous thought, only this time he brings everyone (all) into the concept, rather than singling out the Jews. "All who rely on works..." And this brings us back to the idea he started in Chapter one, where he tells them that they have followed a "different gospel." They had turned away from the gospel of grace through faith, and once again were chasing a false gospel built on works or acts of obedience.
No one is justified by before God by the law. No one. The righteous live by faith, and the law is not of faith. I know this one confuses a lot of people. Either we want to take it to one extreme or the other. Either we want Christianity to be about obedience to an external set of regulations, or we want to make it about a complete freedom from such regulations (See Romans 6:1,2) The truth lies in between, where we obey the ideals of the law because of our love for God, rather than being bound by the law or ignoring any law.
Jesus certainly did not live a life that was free from the law, nor did he preach such a life for his followers. His preacher actually centered on an idea much more difficult and much more demanding. It was that idea that we love God, and surrender fully to him out of our gratitude and love for him. To quote Matt Chandler's thought, "Heaven is not a place for people who do not want to go to hell, it is a place for those who love God." Now, because of Jesus, the promise made to Abraham can be realized. Now, we can live by the Spirit of God and not by the law. But that Spirit will never take us to a place where we violate God's law, because the Spirit is from God and is God!