Leader’s guide · 12 weeks

Leader’s guide: The Mortification of Sin (For Teens)

John Owen

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Using this guide with a class? See Ochorus for schools or homeschool families

This guide takes your group through “The Mortification of Sin (For Teens)” in twelve weeks, one chapter a week. It retells John Owen’s famous book, first preached to Oxford students and published in 1656, about how a Christian fights the sin that won’t go away. “Mortify” means “put to death”, and Owen’s answer is not grim self-effort but the Holy Spirit and Jesus. It is written for teens aged about 13 to 18 and suits a youth group, a homeschool or a small group, especially one ready for honest, serious talk about temptation and growth.

Each session takes about 30 to 40 minutes. Open by saying the memory verse together (3 minutes). Read the chapter, either aloud together or beforehand at home (8–10 minutes). Talk through the chapter’s three questions, which come with answers to help you (10 minutes). Do the activity (10 minutes). Then close by praying the chapter’s prayer, or one of your own (2 minutes).

To prepare, read the chapter yourself and look over the activity; most weeks need only paper and pens. Because this book is about sin, the most important thing you can do is keep it safe: never ask anyone to name their own sins aloud, keep personal reflection on paper that stays private, and talk in general examples rather than confessions. Some teens carry heavy guilt and some struggle with habits that feel out of control, so keep coming back to Owen’s own centre, the love of Christ and the work of the Spirit. Chapter 4 says plainly that killing sin never means hurting yourself, chapter 9 names habits such as pornography, alcohol, vaping and drugs, and chapter 11 speaks to guilt that will not lift; make sure the group knows they can talk to you or another trusted adult privately, and follow your church’s safeguarding procedures if anyone tells you they are being harmed or harming themselves.

Week 1 — The Man Who Wrote “Kill Sin”

John Owen, born in 1616, went to Oxford at about twelve, but for years he knew a lot about God without being sure God was his, until an unknown stand-in preacher brought him assurance around 1642. He went on to lead Christ Church and Oxford University, preached to students about sin that wouldn’t go away, and turned those sermons into The Mortification of Sin in 1656, despite later losing his post and all but one of his children. The book’s famous line is “be killing sin or it will be killing you,” but its answer is the Holy Spirit and Jesus, not trying harder. The big idea: this book is for anyone with a sin they keep falling into, and God has real help for them.

“For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.” — Romans 8:13 (KJV)

Memory verse

For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live.

Romans 8:13

Talk together

  1. What happened to Owen around 1642?

    He heard an unknown preacher, standing in for a famous one, preach on “Why are ye fearful, O ye of little faith?”, and through it he received assurance of God’s love.

  2. Who first heard the sermons that became The Mortification of Sin?

    Students at Oxford University, where Owen was Vice-Chancellor.

  3. What does “mortify” mean?

    To put to death.

Activity

Owen’s Story

You will need: Paper and pens

  1. Read out the key moments of Owen’s life from the chapter: Oxford at twelve, years of uncertainty, the stand-in preacher, the famous book, the hard losses.
  2. In pairs, talk about why someone who knew so much about God could still lack peace with him.
  3. As a group, put Romans 8:13 into your own words, making sure to keep both “by the Spirit” and “you will live”.
  4. Ask everyone to write privately, on paper they keep, one habit they would like God to help them put to death, and to pray over it during the week.

Read chapter 1

Week 2 — Be Killing Sin

Owen builds his book on Romans 8:13 and says that killing sin is daily work for every Christian, even the best, because sin still lives in believers and never takes a day off. He compares it to a gardener who keeps pruning season after season, and warns that someone who stops striking before the enemy is dead has done only half the job. The chapter adds that this is not about being anxious and grim, but about steady training, and that the goal is life. The big idea: be killing sin every day, because the fight leads to life.

“Mortify therefore your members which are upon the earth.” — Colossians 3:5 (KJV)

Memory verse

Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry.

Colossians 3:5

Talk together

  1. Which Bible verse is Owen’s whole book built on?

    Romans 8:13: “if ye through the Spirit do mortify the deeds of the body, ye shall live.”

  2. Why does Owen say we must fight sin every day?

    Because sin is still in us and never takes a day off; it is most dangerous when it seems quiet.

  3. What does Owen say about someone who stops striking an enemy too soon?

    They have only done half their work.

Activity

Daily Training

You will need: Paper and pens

  1. Ask anyone who trains for a sport, a musical instrument or a skill to describe what happens if they stop practising for a month.
  2. Read Owen’s line aloud: “be killing sin or it will be killing you,” and talk about why he compares the Christian life to daily training rather than a one-off effort.
  3. Talk about Owen’s picture of still, deep water, and why sin may be most dangerous when it seems quiet.
  4. Have everyone plan privately a two-minute evening review for this week: thanks for victories, honesty about failures, and a prayer for tomorrow.

Read chapter 2

Week 3 — Sin Never Stays Small

Owen warns that sin always aims at the utmost: an unclean glance would become adultery and a small doubt would become unbelief, if allowed to grow. Sin starts modestly, asking only a little room, then keeps the ground it gains and pushes for more, while we compare ourselves only with last week and think we are not that bad. The chapter is clear that small sins are not as bad as the biggest, but they are seeds, like a snowball that is easiest to stop before it starts rolling. The big idea: take small sins seriously, because sin never wants to stay small.

“But every man is tempted, when he is drawn away of his own lust, and enticed. Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death.” — James 1:14–15 (KJV)

Memory verse

But each person is tempted when he is lured and enticed by his own desire. Then desire when it has conceived gives birth to sin, and sin when it is fully grown brings forth death.

James 1:14–15

Talk together

  1. What does Owen mean by “Sin aims always at the utmost”?

    Every temptation, if allowed to grow, would go all the way to the worst sin of its kind.

  2. How does sin trick us when it first appears?

    It looks modest and asks for little, but once it gets a foothold it keeps its ground and pushes further.

  3. Why do we often not notice sin growing?

    Because we compare ourselves with last week instead of where we started, and think we are not that bad.

Activity

Seed to Snowball

You will need: A large sheet of paper and pens

  1. Draw a hill with a small snowball at the top and a huge one at the bottom.
  2. As a group, pick a general example from the chapter, such as a small lie, a bit of jealousy or a flash of irritation.
  3. Fill in the stages down the hill together, showing how it might grow if it were fed every day.
  4. Mark on the drawing the easiest point to stop it, and talk about why.
  5. Ask everyone to think privately of one “small” habit they could stop feeding this week.

Read chapter 3

Week 4 — Not in Your Own Strength

Owen says that trying harder on its own will never kill sin: “A man may easier see without eyes, speak without a tongue, than truly mortify one sin without the Spirit.” Fighting sin in our own strength, by our own methods, to feel good about ourselves, is the heart of false religion, which is why Owen rejected harsh vows and punishing the body. The chapter says very clearly that killing sin never means hurting yourself, and that the fight begins only when a person is joined to Christ by faith and receives his Spirit. The big idea: the power to kill sin is the Holy Spirit’s, so ask for his help instead of only trying harder.

“Not by might, nor by power, but by my spirit, saith the LORD of hosts.” — Zechariah 4:6 (KJV)

Memory verse

Not by might, nor by power, but by my Spirit, says the LORD of hosts.

Zechariah 4:6

Talk together

  1. What does Owen say is easier than killing one sin without the Spirit?

    Seeing without eyes or speaking without a tongue.

  2. What does Owen call the “soul and substance of all false religion”?

    Trying to kill sin by your own strength and methods in order to make yourself righteous.

  3. Does killing sin mean punishing or hurting your body?

    No. Owen rejected harsh bodily practices; it is the Spirit’s work in the heart, and anyone hurting themselves should tell a trusted adult or doctor.

Activity

Not by Might

You will need: Paper and pens

  1. List together the ways people try to beat a bad habit by willpower alone, such as resolutions, gritting your teeth or making promises.
  2. Talk about why Owen says these fail on their own, and why harsh self-punishment misses the point entirely.
  3. In pairs, write a short prayer asking the Holy Spirit for strength in the moment of temptation.
  4. Have everyone copy the prayer somewhere they will see it before their usual temptation this week.

Read chapter 4

Week 5 — Fighting for Life

Owen says the vigour, power and comfort of our spiritual life depend on killing sin, which is like pulling weeds that strangle a plant. Unmortified sin weakens and darkens the soul, takes away peace and makes prayer, Bible reading and joy hard, while sin being put to death brings prayer, joy and love back to life. The chapter contrasts sin’s false promises with Jesus’ words about the thief and the abundant life, and recalls Owen’s warning about Christians who grew cold by slowly ceasing to watch. The big idea: killing sin is not losing life but clearing space for it.

“The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly.” — John 10:10 (KJV)

Memory verse

The thief comes only to steal and kill and destroy. I came that they may have life and have it abundantly.

John 10:10

Talk together

  1. What does Owen say depends on killing sin?

    The vigour, power and comfort of our spiritual life.

  2. What does unmortified sin do to the soul, according to Owen?

    It weakens and darkens it, takes away peace, and makes us less useful.

  3. What did Jesus say about the thief and about himself in John 10:10?

    The thief comes to steal, kill and destroy; Jesus came so that we might have life more abundantly.

Activity

What Sin Promises

You will need: Paper and pens

  1. Draw two columns: “What sin promises” and “What sin actually takes”.
  2. As a group, fill in the first column with what temptation often seems to offer, such as fun, freedom or popularity.
  3. Fill in the second column from the chapter, such as peace, joy, prayer and closeness to God.
  4. Read John 10:10 aloud and talk about how Jesus’ promise compares.
  5. Ask everyone to choose privately one practical step against something that drains life from them this week.

Read chapter 5

Week 6 — What Killing Sin Is Not

Before saying what killing sin is, Owen lists what it is not: it is not getting rid of sin completely in this life, not merely hiding it, not having a calm personality, not swapping one sin for another, and not a burst of effort after a crisis. Of someone who swaps sins he says, “He hath changed his master, but is a servant still,” and he compares post-crisis calm to an enemy that pulls back to regroup. The chapter adds that a crisis can wake us up, but real change is steadier and deeper. The big idea: real change happens in the heart, not just on the surface.

“Not as though I had already attained, either were already perfect: but I follow after, if that I may apprehend that for which also I am apprehended of Christ Jesus.” — Philippians 3:12 (KJV)

Memory verse

Not that I have already obtained this or am already perfect, but I press on to make it my own, because Christ Jesus has made me his own.

Philippians 3:12

Talk together

  1. Why should we not despair if temptation is still there?

    Because sin is not completely destroyed in this life; even Paul said he had not yet attained.

  2. What does Owen mean by “He hath changed his master, but is a servant still”?

    Giving up one sin while another takes its place is not real freedom; the heart is still serving sin.

  3. Why isn’t a burst of effort after a crisis enough?

    Because sin often goes quiet after a crisis and then comes back; real change is steadier and deeper.

Activity

Five Nots

You will need: Five slips of paper and pens

  1. Write each of Owen’s five “nots” on a separate slip and lay them out.
  2. Read out a few made-up scenarios, such as someone who stops one bad habit only to start another, and have the group match each to the right “not”.
  3. Talk about which of the five mistakes is easiest for teens to make, keeping to general examples.
  4. Ask everyone to think privately about which “not” might be true of them, and to talk to God about it this week.

Read chapter 6

Week 7 — What Killing Sin Is

Owen says killing a sin has three parts: weakening its pull so it rises less often and less strongly, constant fighting that includes knowing how the sin works in you and refusing to excuse it, and success, as frequent victories by the Spirit loosen its grip over time. He notes that a sin is often strongest where it fits our temperament or circumstances, so different people face different battles. The chapter stresses that this is a process, more like getting fit than flicking a switch, and that being filled with the Spirit leaves less room for sin. The big idea: walk by the Spirit, and over time sin loses its grip.

“This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh.” — Galatians 5:16 (KJV)

Memory verse

But I say, walk by the Spirit, and you will not gratify the desires of the flesh.

Galatians 5:16

Talk together

  1. What are Owen’s three parts of killing sin?

    Weakening the sinful habit, constant fighting against it, and success over it.

  2. Why might your hardest battles be different from a friend’s?

    Because sins grow stronger when they fit a person’s temperament, way of life or usual situations.

  3. Is killing sin a single moment or a process?

    A process, more like getting fit than flicking a switch.

Activity

Know Your Enemy

You will need: Paper and pens

  1. Explain Owen’s three parts: weakening the sin, constant fighting, and success.
  2. As a group, take a general example such as losing your temper, and work out together its usual triggers, its usual excuses and one way to walk by the Spirit at that moment.
  3. Then give everyone a few minutes to do the same privately on paper for a sin they want to fight.
  4. Talk about why the chapter compares this to getting fit rather than flicking a switch.

Read chapter 7

Week 8 — All of It, Not Just One

Owen warns that someone who fights only the one sin that troubles them, while being careless about prayer, Scripture and how they treat people, will not win, because their real motive is often self-love: they want relief, not holiness. True mortification rests on hatred of sin as sin and “a sense of the love of Christ in the cross,” since Jesus bled for every sin, not only the ones that bother us. Like a sore caused by poor health, one sin is best healed by caring for our whole walk with God. The big idea: ask God to search your whole heart, not just fix one problem.

“Search me, O God, and know my heart: try me, and know my thoughts: and see if there be any wicked way in me, and lead me in the way everlasting.” — Psalm 139:23–24 (KJV)

Memory verse

Search me, O God, and know my heart! Try me and know my thoughts! And see if there be any grievous way in me, and lead me in the way everlasting!

Psalm 139:23–24

Talk together

  1. Why won’t fighting only one troubling sin work, according to Owen?

    Because if we are careless in the rest of our walk with God, our fight is driven by self-love, and the sin will not be truly mortified.

  2. What should lie underneath our fight against sin?

    Hatred of sin as sin, not just because it troubles us, and a sense of Christ’s love on the cross.

  3. What picture does Owen use about a sore and an unhealthy body?

    Treating only the sore won’t cure it if the whole body is unhealthy; we must care for our whole walk with God.

Activity

The Whole Garden

You will need: Paper and pens

  1. Draw a simple garden with several beds labelled prayer, Bible reading, friendships, family, words, and time online.
  2. Talk about Owen’s point that one weedy bed is hard to fix if the rest of the garden is neglected.
  3. Discuss the difference between hating a sin because it makes us feel bad and hating it because it grieves God.
  4. Ask everyone to pray Psalm 139:23–24 quietly and write down privately anything God brings to mind.

Read chapter 8

Week 9 — Warning Lights

Owen lists warning lights that show a sin has become especially serious: it has gone on a long time, you have made peace with it, it keeps winning, you only resist it for fear of consequences, and God has already warned you and you carried on. When these appear, extraordinary remedies are needed, and one of them is not fighting alone, since Hebrews tells believers to exhort one another daily. The chapter urges anyone whose habit feels out of control, such as pornography, alcohol, vaping or drugs, to talk to a trusted adult, a youth leader or a doctor. The big idea: if the warning lights are flashing, don’t panic and don’t fight alone.

“But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.” — Hebrews 3:13 (KJV)

Memory verse

But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin.

Hebrews 3:13

Talk together

  1. Name two of Owen’s warning signs that a sin has become dangerous.

    Any two of: it has gone on a long time; you have made peace with it; it keeps winning; you only fight it out of fear of consequences; it has continued despite God dealing with you about it.

  2. Why is making peace with a sin so dangerous?

    Because it stops us feeling the need to fight it, and can turn grace into an excuse to keep sinning.

  3. According to Hebrews 3:13, how does God help us not to be hardened by sin?

    Through other believers exhorting and encouraging us daily.

Activity

Dashboard Check

You will need: Paper and pens

  1. Draw a car dashboard with five warning lights and label each with one of Owen’s warnings.
  2. Talk about what a sensible driver does when a warning light comes on, and how that compares with sin.
  3. As a group, list the kinds of people a teen could safely talk to about a struggle, and what makes someone trustworthy.
  4. Give everyone a few private minutes to check their own dashboard on paper, and encourage anyone with a flashing light to speak to a trusted adult this week.

Read chapter 9

Week 10 — Stop It Early

Owen gives two practical pieces of advice: watch against the occasions and opportunities your sin usually uses, and rise against the very first stirrings of temptation without giving it the least ground. He warns against saying “Thus far it shall go, and no farther,” because sin given one step takes another, like water that runs its course once it breaks out of a channel. The chapter applies this to ordinary life, such as not keeping your phone in your room at night if that is where you fall. The big idea: change the situation and turn away in the first few seconds.

“Watch ye and pray, lest ye enter into temptation. The spirit truly is ready, but the flesh is weak.” — Mark 14:38 (KJV)

Memory verse

Watch and pray that you may not enter into temptation. The spirit indeed is willing, but the flesh is weak.

Mark 14:38

Talk together

  1. What does Owen tell us to watch against?

    The occasions and opportunities our particular sin usually uses.

  2. What does “Rise mightily against the first actings” mean?

    Fight temptation at its very first moment, before it gets any ground.

  3. Why is “Thus far it shall go, and no farther” a dangerous idea?

    Because once sin is allowed one step it will take another; like water in a channel, once it breaks out it runs its course.

Activity

Danger Zones

You will need: Paper and pens

  1. As a group, list common times and places where teens face temptation, such as late at night, being bored or lonely, certain apps or certain group chats.
  2. For each, brainstorm one practical change that would make it easier to say no.
  3. Talk about Owen’s warning against letting temptation in “just a crack”.
  4. Ask everyone to write privately their own top two danger situations and one change for each.

Read chapter 10

Week 11 — Don’t Fake Peace

Owen urges believers to take sin seriously by talking honestly to themselves, asking how they can face the Lord Jesus and whether they will grieve the Spirit who sealed them, so that Christ’s love makes sin look as ugly as it is. He also warns against speaking peace to ourselves before God speaks it, grabbing a quick “it doesn’t matter” instead of truly turning; our part is to confess, turn and trust, and giving peace is God’s. The chapter is clear that God loves to speak peace and does forgive, and that anyone who can never feel forgiven should talk to a pastor or trusted adult. The big idea: real peace comes from God, and it goes together with real change.

“I will hear what God the LORD will speak: for he will speak peace unto his people, and to his saints: but let them not turn again to folly.” — Psalm 85:8 (KJV)

Memory verse

Let me hear what God the LORD will speak, for he will speak peace to his people, to his saints; but let them not turn back to folly.

Psalm 85:8

Talk together

  1. What questions does Owen suggest we ask ourselves about sin?

    Questions like “What can I say to the dear Lord Jesus?” and “Shall I daily grieve that Spirit whereby I am sealed?”

  2. What does it mean to speak peace to yourself too quickly?

    Grabbing a quick comfort that sin doesn’t matter, without truly turning from it or listening to God.

  3. According to Owen, whose job is it to give peace?

    God’s; our part is to use the means of seeking peace, such as confessing, turning and trusting.

Activity

Real Peace, Fake Peace

You will need: Paper and pens

  1. Draw a road with a ditch on each side, labelled “It doesn’t matter” and “I’ll never be forgiven”.
  2. As a group, write in the middle of the road the steps Owen describes: confess honestly, turn from it, trust Christ, receive his peace.
  3. Read 1 John 1:9 together and talk about how it keeps us out of both ditches.
  4. Remind everyone that if guilt ever feels stuck, a pastor or trusted adult can help.

Read chapter 11

Week 12 — Look at Jesus

Owen’s most important direction is to set faith to work on Christ, whose blood is the great remedy for sin-sick souls, with the promise that we will live to see our sin dead at our feet. Even when we are weary of fighting, there is enough in Christ, as the prodigal remembered there was bread enough in his father’s house, and looking at Jesus on the cross makes sin look ugly and freedom desirable. Two days before his death in 1683, Owen wrote that he was going to him “who hath loved me with an everlasting love.” The big idea: the fight against sin ends not with our willpower but with Christ’s love, so keep looking at Jesus.

“Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God.” — Hebrews 12:2 (KJV)

Memory verse

Looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God.

Hebrews 12:2

Talk together

  1. What is Owen’s most important direction for killing sin?

    Set faith at work on Christ; his blood is the great sovereign remedy for sin-sick souls.

  2. What does the prodigal son’s “bread enough” teach us?

    When we feel weak and ready to give up, there is enough in Christ to help us.

  3. What did Owen write two days before he died?

    “I am going to Him whom my soul hath loved, or rather who hath loved me with an everlasting love.”

Activity

Looking at Jesus

You will need: Bibles, paper and pens

  1. Read Luke 23:33–46 aloud slowly while everyone listens.
  2. Give everyone two quiet minutes to write down one thing they noticed about Jesus in the passage.
  3. Read Owen’s last letter aloud and talk about why he corrected himself from “whom my soul hath loved” to “who hath loved me”.
  4. Look back over the twelve weeks and ask each person to name, if they wish, one thing they have learned about fighting sin.

Read chapter 12