In verse 15, the translation should actually read “What then? Shall we commit an act of sin?” Since grace is so free, shouldn’t we now tolerate some sin? Paul says we have to avoid sin because we can only choose one Master. To go back and forth brings chaos. We must choose our master and consistently do the will of the master we choose. Either our sin self rules and brings death or God rules and brings eternal life. 19th century theologian, Fredrick Godet put it this way:
“Every act of will, whether in the direction of good or of evil, as it passes into reality, creates or strengthens a tendency which drags man with increasing force, til it becomes altogether irresistible. Every free act, then, to a certain degree determines the future.”
This is why we ourselves have to be careful not to sin when confronting someone else about sin. If we, through thought or deed, sin in our interactions with those who think differently or act differently from how the Bible tells us we should be, Satan will use that sin - our own sin - against us and against God.
Who is your master? One of the most important things for us to focus on always is who our Lord is. Every action, every thought, everything we do shows who our master is. This is why it is so very critical that we examine every thing we do or say and make sure that they show God as our Lord and not ourselves. Think before you do something, think before you say something, think before you click send on that email or post. Do they reflect God’s will or yours? Will people see God or will people see you?