Why does sin not have dominion over believers?

The Apostle Paul illustrates that sin cannot reign in the hearts of believers because they are not under the law but under grace (Romans 6:14). This grace is transformative; it brings about a new heart and spirit, enabling believers to serve God in holiness rather than succumbing to the dominion of sin. As Romans 7:6 indicates, we now serve in newness of spirit, which is empowered by grace and not by the oldness of the letter, illustrating that our identity in Christ secures us from the bondage of sin.