Furthermore, the Grace of God brings us salvation and "teaches us to say no to sin" (Titus 2:11-12). The law could not teach us to say no to sin. Rather, it arouses our sinful passions (Romans 7:5). "I would not have known sin, except through the law, for I would not have known about coveting, if the law had not said, `You shall not covet.' But sin, taking opportunity through the commandment produced in me coveting of every kind (Romans 7:7-8).
The law can never teach us how to live righteously before God. In I Corinthians 15:55, Paul said, "The power of sin is the law". The reason the power of sin is the law, is that it is our flesh that tries to obey laws, and our flesh cannot please God. If you care about what the Bible says, God gave us the law to show us our sins, to show us our sinfulness, and to lead us to Christ. But He didn't give us His laws to make us holy! Galatians 2:21 teaches us that if God could have given us a law that could make us righteous, then Christ died for nothing!
The New Covenant is not laws against sin, but Christ living in you and me, so that as we walk in His Spirit we don't sin. The problem with law is our flesh, which tries to obey it. But God has given His Spirit to everyone who believes Jesus, that we may walk rightously, in His Spirit, not in our own fleshly efforts at living good enough lives by obeying the law.
It seems that nothing is harder for a Christian to grasp, than what Paul meant, when he said, "It is no longer I, but Christ!" It really is no longer I. It is Christ, living His own life through me, as I trust Him by believing what He said to me through the Spirit of Truth.
Don't make the fleshly mistake of thinking you can figure it all out by just studying the words of Christ in the Gospel records. Remember what He told the disciples the night He was betrayed, "I have many more things to teach you, but you cannot bear them now. But when He, the Spirit of Truth, comes, He will guide you into all truth... (John 16:12-13) The things that Jesus tells us through Paul's writings are just as much the word of God as what Jesus spoke through His own lips. The same is true of the letters to the churches written by John, Peter and the other New Testament writers.
There is so much that God wants to teach us, if we are ready to learn. The Spirit of truth will guide us into all the truth..."