The Law never succeeded in producing righteousness—the failure was always the weakness of human nature. But God has met this by sending his own Son Jesus Christ to live in that human nature which causes the trouble. And, while Christ was taking upon himself the sins of men, God condemned that sinful nature. So that we can meet the Law’s requirements, so long as we are living no longer by the dictates of our sinful nature, but in obedience to the promptings of the Spirit.
Romans 8:3-4 (Phillips)
We are saved by the finished work of Jesus Christ alone through faith.
Since we did not earn our salvation by our righteousness, we cannot lose our salvation by our unrighteousness. However, if we continue to sin, we have not fully understood the gospel. This is because Jesus set us free not only from the punishment of sin, but also from the power of sin. The way to walk in freedom from sinful desires is by walking in the Spirit.
If you strive to keep the law, you will never succeed, but if you rest in Jesus, you will never fail. According to the Apostle Paul, when we walk with the Spirt, the righteous requirement of the Law is fulfilled in us, not by us. How? While the Old Covenant requires people to keep the Law to be righteous before God, the New Covenant declares us righteous in Christ, thus qualifying us to walk righteously.
This is a faith walk, and grace has empowered us to live rightly for God. Thus, the Christian life is about drawing from the vast reservoir of our righteousness in Christ rather than living up to a standard set by the Law. His Holy Spirit in us will inscribe Spirit-filled words (2 Corinthians 3:3; Ezekiel 11:19) that are life giving and transforming, enabling us to go beyond what the Law requires. When we grasp the implication of our life in Christ, we will live boldly and not in fear.