Paul says that if we walk in the Spirit, we will not sin ("fulfill/act out the lust of the flesh"). Why is that? Because there is no evil in the Holy Spirit. The Holy Spirit is God. So, if you are living your life harmoniously with the Holy Spirit, you will not sin. There is no point of harmony between the flesh and the Holy Spirit. There is no righteousness in the sin-nature. As Paul said, "Nothing good dwells in my flesh" (Romans 7:18).
The sin-nature is your enemy. The reason you, as a Christian, cannot do all the good things you would choose to do is because the sin-nature is obstructing you. The sin-nature is like scar tissue in a joint, binding up the muscles. Your conscience, when it is instructed by the Word of God, knows what is right. Your heart, which has been renewed by the Holy Spirit through your faith in Christ, instinctively desires to do what is right. But your sin-nature is still with you, gluing up the works.
Here is a scary thought: does this problem, this inner struggle, mean that you are forced back under the death-curse of the Law? When the flesh re-asserts itself in your life and you are still weak in your maturitty, does that mean you are going to hell? Not at all.
Those who are led by the Spirit are not under the law of death. Like sheep cared for by the shepherd, all Christians are under the care of the Holy Spirit. If the Holy Spirit is in your life, that means God has forgiven you of your sins! You would not have the Spirit of God if you were not redeemed from the curse of the law. The Spirit's presence in your life -- even as His presence creates that inner tension between conviction and performance -- His very presence should give you confidence that you are not under the law of sin and death. The curse of the law is gone, and the proof of it is that you have the Spirit of God in your life That's good news!
You need this confidence, so that you can move forward in your Christian life.