“But thanks be to God, that you who were once slaves of sin have become obedient from the heart to the standard of teaching to which you were committed” (v17). Now that they were under grace and set free from sin’s control, Paul urged the Roman believers to actively offer themselves to God for His righteous purposes (v13). Many of them were doing this, obeying God “from the heart” and leaving their old lives behind. They realized that a life of sin only produces death, while righteousness leads to more life (v21-22).
“Present yourselves to God as those who have been brought from death to life” (v13). Our redeemed lives belong to God, to be used for His kingdom purposes.