“Let not sin therefore reign in your mortal body, to make you obey its passions.
Every moment of every day, even the most committed follower of Jesus, is tempted to allow sin to reign in this body. Every moment of every day, sin is trying to make you obey its passions.
Therefore, every follower of Jesus must not “let” sin have dominion in our lives. Every day, followers of Jesus must choose to let him, not sin, reign within. No one else can do it for you. It’s everyone’s battle, even those who have relinquished their lives to Jesus. But only you can fight it. It’s yours and no one else’s battle.
But this is true too: every day, when you are faithful, sin should lose a bit of its grip over your life. Every day, as you let Jesus, not sin, reign, the grip and power of sin becomes less. You progressively look more like Jesus. You slowly move toward your ultimate, glorified, perfected state in heaven.
Today, don’t allow sin to reign in you! It’s your choice! That’s what Paul, in this verse, is trying to teach all of us today.