How do we know that once saved, a believer will not be dominated by sin?

The promise in Romans 6:14 that 'Sin shall not have dominion over you' is based on the truth that believers are not under the law but under grace. This foundational truth affirms that the power of sin has been broken in the life of a believer, ensuring that they will not return to a state of bondage to sin. The continual presence of sin may cause struggles, but for those genuinely born again, God's grace secures them from ultimate defeat. Therefore, the assurance lies in the completed work of Christ and His sustaining grace that guarantees believers’ ongoing faith until glorification.