Imagine you contracted a deadly infection. It started at your hand, and you had mere seconds to cut it off before it spread to the rest of your body, hollowing you out, killing you. In World War Z, the character Segen is bitten on her hand by a zombie. Gerry Lane (Brad Pitt) immediately cuts off her hand, saving her life. She was desperate, so Gerry did the unthinkable. And while she no longer had a hand, she retained her life.
In the Sermon on the Mount, Jesus says something that we often gloss over: "If your right eye causes you to sin, tear it out and throw it away." (Matthew 5:29)
One sentence later, He utters another extreme statement: "If your right hand causes you to sin, cut it off and throw it away." (Matthew 5:30)
His rationale? "It is better that you lose one of your members than that your whole body go into hell." (Matthew 5:30)
If you're just reading this, it's easy to gloss over the extreme measures that Jesus says we should go to to get rid of sin. Get rid of your eye? Your hand? And for most, it probably would have been their dominant features.
Some of us might hear it and think, "Yes, I'm going to be more moral." Others might think, "That's dumb." Both sides miss the point.
Notice Jesus' rationale again. It is better to lose one part of your body than to lose your whole body to hell. He's using a metaphor here. It begs the question, when would you cut off your hand? When would you pluck out an eye? Much like Gerry Lane helped with Segen, you would do it when it was the only way to save your life.
Jesus is comparing sin (particularly lust) to a disease or an infection similar to gangrene. Gangrene infects one part of the body, and if you don't kill it before it spreads, it eventually kills you. Sin does the same thing. Sin is in our hearts. And if we let it reign in our lives, it will eventually deaden our senses, deaden our morality, and will destroy our souls. But if we kill it, our lives flourish, because we stop the infection.
But how can cutting off our dominant hand or our dominant eye, improve quality of life? It improves it by saving it from sin and death, and the fires of hell. It may be extreme, and it may hurt in the short-term. But it proves profitable in the long run.
So what does it look like to kill sin?
First, look to the cross: The way to a new heart is not changing your behavior. It's by receiving a heart transplant. The Gospel not only saves us from hell, but it transforms us because it replaces a heart of stone with a heart of flesh.
Second, observe where you are tempted: There are certain videos on youtube that I just can't watch. They aren't explicit. They aren't sinful in and of themselves. But they contain language and images that sometimes are unhelpful and tempt me towards the road of sin, and influence my thoughts. I need to observe these and other times where I might be tempted, so that I can do the next step.
Third, make a plan, and fight: So think about when you're tempted. Confess those to someone you trust (probably helpful if it's someone who is the same gender, if it has to do with sexual sin). And get specific. Download a filter, get rid of your app store, disable social media if you have too. Refuse to watch movies with specific language or content (IMDB's parental guide is a great resource!). Cut off anything that might lead to sin.
Fourth, see how God gives you life, and praise Him: It's amazing, that when you stop lusting, you can start loving. You can see people as souls, instead of objects. You can praise Him for His design of life, and people, and attraction, and love. Killing sin will be painful at first. How could it not, if it's as extreme as cutting off a limb? But it's so we might find more joy in God, and in His creation.