Kill the Sin That Kills Your Peace

There is a passage in Mark 9 that most people assume they understand before they have really sat with it. On the surface, it reads like a radical call to self-denial — cut off your hand, tear out your eye, throw a millstone around your neck. Harsh, vivid, arresting language. But if you stop there, you have missed the deeper current running beneath every verse.

This passage is about Christians getting along with each other. It is about the kind of radical, costly, painful dying to self that makes genuine peace with other believers possible. And it begins and ends in exactly the right places. It opens with a disciple trying to shut down someone who is casting out demons in Jesus' name, and it closes with Jesus saying simply: be at peace with one another.

Everything in between is the path from one to the other.

The Problem of Ecclesiastical Pride
John comes to Jesus with what he seems to think is a responsible report. Teacher, we saw someone casting out demons in your name, and we tried to stop him because he was not following us. Read that carefully. The disciples had just failed to cast a demon out of a suffering boy. And now here is someone they do not recognize, someone outside their circle, doing the very thing they could not do. And their response is not celebration. It is suspicion and suppression.

There is a version of this that lives in churches today. It is the slow, subtle drift toward believing that your tradition, your form, your style, your authority structure has so optimized following Jesus that anything outside it is at best suspect and at worst dangerous. Before long, the unspoken logic becomes something like: it would be better for people not to go to church at all than to go to one that does not look like ours.

Jesus blasts that thinking away. He tells John not to stop the man. He tells him that anyone doing a mighty work in his name is not going to turn around and speak evil of him. The one who is not against us is for us.

The word "us" matters here. It is not a blank check for theological indifference. There are first-order convictions — the bodily resurrection of Christ, the Trinity, justification by faith alone, the exclusivity of Christ — that define whether someone is inside or outside the faith. These are not negotiable. But there are secondary and tertiary matters where genuine Christians disagree, and the mistake is treating those secondary things as if they were primary. When that happens, unnecessary division follows. People who belong to the same "us" start treating each other like strangers or enemies.

The Cup of Water You Did Not Expect to Need
Jesus follows this with something quietly subversive. He says that whoever gives you a cup of water because you belong to Christ will by no means lose his reward. Notice the direction of that sentence. The cup of water is being given to the disciples. To them. To the very people who wanted the mighty, public-facing role of casting out demons.

Following Jesus is not only about doing great things for others. It also means being humble enough to be the one who receives. It means accepting the meal someone brings you, the honest word a friend speaks into your life, the hug from someone who simply sat with you in a hard season. If your vision of the Christian life is only you doing impressive things, you will find yourself in a kind of pride that makes you useless to the people around you and brittle in your own soul.

The Gravity of Causing Others to Stumble
Then comes the millstone. Whoever causes one of these little ones who believe in Jesus to sin — it would be better for that person to be thrown into the sea with a millstone around their neck. The severity is intentional. Jesus wants his disciples to feel the weight of what it means to be the reason someone else falls into sin.

And then he turns it inward. If your hand causes you to sin, cut it off. If your eye causes you to sin, tear it out. He is not giving surgical instructions. He is giving a measure of how seriously sin should be taken. The language is meant to approximate the actual pain of genuine repentance. Sin is as attached to us as our own limbs. It is what we look at, what we reach for, where we choose to go. Getting rid of it is not a minor inconvenience. It is a tearing away of something that has become part of us.

Can You Taste the Salt?
This is where the passage arrives at its most searching question. Jesus says that everyone will be salted with fire, and that salt is good, but if salt loses its saltiness, it is useless. Salt does not just preserve — it heightens flavor. It makes you taste what is actually there.

The fire of God's judgment against sin is meant to function the same way. It is meant to make the reality of sin vivid and weighty. It is meant to make holiness and eternal life taste like what they actually are — worth everything.

Isaiah 66 captures both sides of this. The Lord comes in fire to judge sin. But Isaiah 66 is not primarily a passage about terror. It is primarily a passage about the glory of what God is building — a new Jerusalem, a gathered people from every nation, a world where his glory fills everything. The question Isaiah leaves ringing in the air is the same question Jesus presses in Mark 9: why would you trade any of that for the temporary pleasure of a sin you refuse to cut off?

The logic of this passage runs in one direction. When the judgment of God becomes real to us — when we can taste the salt — we take our sin seriously. When we take our sin seriously, we fight it with everything we have. When we fight it, we stop being the kind of people who wound and cause others to stumble. And when that happens, peace with one another becomes possible.

Have salt in yourselves, Jesus says, and be at peace with one another.

The gospel hope underneath all of this is not that you clean yourself up before you come to Christ. It is that Christ washes you clean — and that the more you believe he is willing and able to do that, the more you will want nothing standing in the way of it. Repentance and faith are not opposites. They are the same movement, made together, again and again, all the way home.