So now anyone who is in Christ Jesus is not judged guilty. That is because in Christ Jesus the law of the Spirit that brings life made you free. It made you free from the law that brings sin and death.
The law was without power because it was made weak by our sinful selves. But God did what the law could not do: He sent his own Son to earth with the same human life that everyone else uses for sin. God sent him to be an offering to pay for sin. So God used a human life to destroy sin.
He did this so that we could be right just as the law said we must be. Now we don’t live following our sinful selves. We live following the Spirit. (Romans 8:1-4 ERV)
Being "in Christ" is not complicated. It means having a personal relationship with Jesus and, so we can do what He says in John 15:4, "Abide in Me...." Once we enter into a personal relationship with Jesus Christ, it is a continuing trust in Him personally as God the Son, and in His work of redemption on the cross.
When it speaks of "the law of the Spirit," it's a reminder that this is an intrinsically spiritual relationship based on the power of Christ's resurrection. The indwelling presence and power of the Holy Spirit enables a believer to be free from the law of sin and death.
We can't free ourselves. We can't make our selves good enough, because we lack that power. But in relationship with Jesus, we gain this power to be free. We become not guilty—free from a sentence of sin and death.
Because Jesus was both human and divine in nature, He could take our place as a payment for sin's debt of death, and destroy its power. Our relationship with Him provides a rightness (or righteousness) with God and His law. So, we have a new way of life.
This new way of life is to follow the guidance of God's Spirit within us rather than our old selfish ways. ©Word-Strong_2016