This is about the law and being released from the law, which is by Christ's sacrifice. Romans is a good study about the law, and sin that continues to be a battle. The battle is due the new nature and old nature. We are new creations in Christ, but as long as we live we still carry around the old nature and have to battle it. A study of these chapters will answer a lot of questions. Note there is not in and out of Christ or alive and dead to sin. There is no indication of any condition on your behavior and nothing about you being sin free when save. It is just the opposite. I cut a few things out just to shorten it up, but it is all good.
Romans 6
Dead to Sin, Alive in Christ. Note it never says you will not sin, but don't live in sin or let sin master you.
1What shall we say, then? Shall we go on sinning so that grace may increase? 2By no means! We died to sin; how can we live in it any longer? 3Or don't you know that all of us who were baptized into Christ Jesus were baptized into his death? 4We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life.
10The death he died, he died to sin once for all; but the life he lives, he lives to God. 11In the same way, count yourselves dead to sin but alive to God in Christ Jesus. 12Therefore do not let sin reign in your mortal body so that you obey its evil desires. 14For sin shall not be your master, because you are not under law, but under grace. Slaves to Righteousness 15What then? Shall we sin because we are not under law but under grace? By no means!
Romans 7 (New International Version)
4So, my brothers, you also died to the law through the body of Christ, that you might belong to another, to him who was raised from the dead, in order that we might bear fruit to God.
Struggling With Sin, everyone does.
14We know that the law is spiritual; but I am unspiritual, sold as a slave to sin. 15I do not understand what I do. For what I want to do I do not do, but what I hate I do. 16And if I do what I do not want to do, I agree that the law is good. 17As it is, it is no longer I myself who do it, but it is sin living in me. 18I know that nothing good lives in me, that is, in my sinful nature.[c] For I have the desire to do what is good, but I cannot carry it out. 19For what I do is not the good I want to do; no, the evil I do not want to do-this I keep on doing. 20Now if I do what I do not want to do, it is no longer I who do it, but it is sin living in me that does it.
21So I find this law at work: When I want to do good, evil is right there with me. 22For in my inner being I delight in God's law; 23but I see another law at work in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin at work within my members. 24What a wretched man I am! Who will rescue me from this body of death? 25Thanks be to God-through Jesus Christ our Lord!
So then, I myself in my mind am a slave to God's law, but in the sinful nature a slave to the law of sin.
Romans 8
Life Through the Spirit not through the law or your actions.
1Therefore, there is now no condemnation for those who are in Christ Jesus,[a] 2because through Christ Jesus the law of the Spirit of life set me free from the law of sin and death. 3For what the law was powerless to do in that it was weakened by the sinful nature, God did by sending his own Son in the likeness of sinful man to be a sin offering.[c] And so he condemned sin in sinful man,[d] 4in order that the righteous requirements of the law might be fully met in us, who do not live according to the sinful nature but according to the Spirit.
Are you saved? What is your mind set on?
5Those who live according to the sinful nature have their minds set on what that nature desires; but those who live in accordance with the Spirit have their minds set on what the Spirit desires.
There is a penalty for the sin in your life, but in Christ that penalty is physical and not spiritual
10 But if Christ is in you, your body is dead because of sin, yet your spirit is alive because of righteousness.