This next section repeats the “what then…by no means” pattern. Again, Paul asks if it is okay to sin, this time because we are under grace. Does this different constitution give us freedom to do what we want. The answer is an emphatic “no”. (v15).
Why? Because our obedience confirms our ownership. We tend to think in terms of obedience or disobedience but in fact, we are always obeying someone or something. If our obedience identifies an unavoidable compulsion then that suggests slavery and slaves have owners. If sin enslaves us then it owns us. We are either slaves to sin or to righteousness (v16).
Paul can thank God because there has been a change. Whilst once we were enslaved in our hearts to sin, obeying teaching that encouraged sin (v17), we now have been set free from that and are slaves to righteousness (v18). Paul says he is having to use human language here to get his point across. It is of course inadequate to describe our relationship to righteousness and God as slavery. However, the language gets across the point that we fully and completely belong to him (v19a).
The consequence should be that we make our whole selves, every part of us, minds, spirits, bodies available to God, to righteousness just as we used to give ourselves over to lawlessness (v19b).
Faithroots 