Healthy spirituality is violent. It’s ruthless. It’s unrelenting. The object of this violence is not people or other religions or competing ideologies. The target is sin. The Puritan pastor and writer, John Owen, famously wrote, “Be killing sin or it will be killing you” (I hope I didn’t just lose you at Puritan). This statement echoes the depiction of sin’s deadly prowess found in the opening pages of Scripture. God warns Cain in Genesis 4:7 “… watch out! Sin is crouching at the door, eager to control you. But you must subdue it and be its master.”

Sin is not passive. It’s ready to strike. It lays in hiding. It desires to rule your life. This is the sinister nature of sin, and if it is not met with violence, it will always bring destruction.

Six Results of Not Battling Sin

Here are some of the most essential truths that flow from the pages of John Owen’s 86-page book on the importance of the killing sin, which show up in his detailed description of the effect that unopposed sin has in the life of a Christian.

Sin is not passive. It’s ready to strike. It lays in hiding. It desires to rule your life.

1. Sin darkens the soul and deprives it of comfort and peace.

Sin will always have this effect. Owen writes, “Every unmortified sin will do two things: it will weaken the soul and deprive it of its vigor. It will darken the soul and deprive it of its comfort and peace.” Throughout Scripture, God’s work and word are associated with light. They have the power to drive out darkness, but sin has the opposite effect. The Gospel of John says, “God’s light came into the world, but people loved the darkness more than the light, for their actions were evil” (John 3:19, NLT). God brings light. Sin always brings death and darkness, and wherever it is present, darkness creeps in robs the soul of comfort and peace.

2. Sin weakens the soul and deprives it of its strength.

“An unmortified lust will drink up the spirit and all the vigor of the soul, and weaken it for all duties.” When Owen uses the word “duties,” he is talking about the spiritual disciplines that of the Christian life, in particular reading the Bible, praying and gaining the spiritual strength that flows from these practices. On the other hand, when sin is allowed to go unchallenged it weakens not only our desire for what produces strength but also our strength itself.

When sin is allowed to go unchallenged it weakens not only our desire for what produces strength but also our strength itself.

This is the Psalmist’s experience, “There is no strength in my bones because of my sin. For my sins have flooded over my head; they are a burden too heavy for me to bear” (Psalm 38:3a–4, HCSB).

3. Sin untunes our hearts.

We are what we love, and if sin is not opposed it will distort our desires and reduce our sensitivity to God’s voice. Owen notes that “It diverts the heart from the spiritual frame that is required for vigorous communion with God; it lays hold on the affections, rendering its object beloved and desirable, so expelling the love of the Father.” Part of what Owen is saying here is that sin wants to own your heart, and if you don’t fight it, it will.

4. Sin makes room for more sin.

When sin is given space in our hearts, it crowds out what should fill our hearts. Owen writes, “Thoughts are the great purveyors of the soul to bring in provision to satisfy its affections; and if sin remain unmortified in the heart, they must ever and [always] be making provision for the flesh, to fulfill the lusts thereof.”

5. Sin redirects our time and attention away from God.

Sin steals the time and attention we need to deepen our relationship with our Creator. Owen says whether it’s consuming ambition or vanity or greed or sexual desire, or any sin issue you can name, if left unaddressed, sin will divert our focus away from what ultimately matters. Sin’s desire is not simply to make people engage in a certain action but to consume their capacity to worship God by monopolizing our time.

6. Sin diminishes the privilege of our adoption.

One of the most beautiful truths of the Christian life is the reality that in Christ we have been brought into the family of God. Sin had separated us, but God, through Jesus’ life, death and resurrection has brought us near. God deeply, personally cares about you as His child.

One of the most beautiful truths of the Christian life is the reality that in Christ we have been brought into the family of God.

Sin diminishes our grasp and awe of this reality. “It is a cloud, a thick cloud that spreads itself over the face of the soul and intercepts all the beams of God’s love and favor. It takes away all sense of the privilege of our adoption; and if the soul begins to gather up thoughts of consolation, sin quickly scatters them.”

So, “Be killing sin or it will be killing you.” Be killing sin so you can live the life God designed you to live walking in the light, strength, and sensitivity to God’s voice, more and more free from sin, focused on God, and continually growing in your amazement of your place in His family!

*John Owen’s book The Mortification of Sin in Believers is part of a larger book entitled Overcoming Sin and Temptation. You can order it here.