Sanctification — how a Christian actually changes
Why growth is slow, what God does and what you do, why willpower fails, and how to keep going through the long ordinary middle of the Christian life.
- Justification is instant and complete; sanctification is gradual and partial until death. Do not expect either to behave like the other.
- It is God's work and your effort — Philippians 2:12-13 puts both in one sentence, with God's work as the reason for yours.
- The ongoing struggle is normal, not evidence of a false conversion (Romans 7, Galatians 5:17).
- Change comes by beholding Christ, not primarily by trying harder (2 Corinthians 3:18).
- You will not be finished in this life. That is not failure; it is the design.
Contents
Someone becomes a Christian. Sins are forgiven, the Spirit indwells, the verdict is settled. And then they find that the temper is still there, the addiction still pulls, and the same failure recurs in month eight that occurred in week one.
Was something missing? No. This is what the New Testament says will happen.
Two different things
Justification is God's legal declaration that you are righteous in his sight, on Christ's record. It is instantaneous, complete, and never revisited (Romans 5:1).
Sanctification is the actual, gradual making-holy of your character. It begins at conversion, continues all your life, and is finished only at glorification.
Hebrews puts both in one verse, and the tenses are the point: "by a single offering he has perfected for all time those who are being sanctified" (Hebrews 10:14). Perfected — done. Being sanctified — in progress. Both are true of the same person right now.
Almost every crisis of assurance comes from expecting sanctification to behave like justification: assuming that if the verdict is settled, the experience should already match it.
The struggle is the normal condition
Galatians 5:17 is the plainest statement, and it is addressed to Christians: "the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do."
Note what this implies. Before conversion there was no war, because there was only one side. The conflict you now feel is not a sign of failure; it is the sign that a second party has arrived.
Romans 7 is Paul's raw version — "I do not understand my own actions. For I do not do what I want, but I do the very thing I hate" (7:15) — ending in a cry, "wretched man that I am! Who will deliver me?" And then, immediately: "thanks be to God through Jesus Christ our Lord!" (7:24-25). The chapter does not end in despair. But it does not end in resolution either. It ends with a person.
God's work and yours, in one sentence
"Therefore, my beloved... work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure" (Philippians 2:12-13).
The connective is the surprise. If Paul had written but — work hard, but remember God is working — we would read it as a division of labour. He writes for. God's working is the reason for yours, not a substitute for it.
Two errors sit either side of this.
Passivity — "let go and let God." It sounds spiritual and it is not in the text. The New Testament is full of imperatives: put to death (Colossians 3:5), flee (1 Corinthians 6:18), pursue (1 Timothy 6:11), train yourself (1 Timothy 4:7), fight (1 Timothy 6:12). Nobody drifts into holiness.
Self-reliance — grit alone. This fails because willpower manages behaviour without touching desire, and desire is what actually drives us. Paul is blunt that rules "are of no value in stopping the indulgence of the flesh" (Colossians 2:23). They restrain the outside and leave the engine running.
How change actually happens
"And we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another. For this comes from the Lord who is the Spirit" (2 Corinthians 3:18).
The mechanism is beholding. You become like what you look at.
This is why the Christian life is not primarily about trying harder to stop doing things. Thomas Chalmers called it the expulsive power of a new affection: a small love is not removed by effort but displaced by a greater one. You do not talk a child out of a piece of broken glass; you offer something better and the hand opens.
Practically, that means the fight against a besetting sin is won less at the moment of temptation than in the hours before it, in what you have been beholding.
How to kill a sin
John Owen wrote the definitive treatment in the seventeenth century and its core is a sentence: be killing sin or it will be killing you.
His method, in brief:
- Name it exactly. Not "I struggle with anger" but the specific person, situation and trigger. Vague confession produces vague repentance.
- Find what is under it. Sin is usually a strategy for getting something — comfort, control, respect, escape. Ask what this sin promises you. That promise is the real opponent.
- Load your conscience with the guilt of it — not to wallow, but to stop negotiating with it.
- Cut the supply lines. Whatever makes it easy, remove. Jesus' language about hands and eyes (Matthew 5:29-30) is hyperbole about a real urgency.
- Do not fight alone. "Confess your sins to one another and pray for one another, that you may be healed" (James 5:16). Sin's chief protection is secrecy.
- Aim at the affections, not only the behaviour. Set the goodness of Christ against the promise the sin is making.
Expect it to be slow
Sanctification is not linear. There are seasons of visible progress and long plateaus where nothing seems to move. Most growth is invisible to the person growing and obvious to those who have known them for a decade.
Two things keep you going.
The direction matters more than the distance. The question is not whether you are where you want to be but whether you are facing the right way and still moving.
It is guaranteed to finish. "He who began a good work in you will bring it to completion at the day of Jesus Christ" (Philippians 1:6). The one responsible for finishing it is not you.
"Beloved, we are God's children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him, because we shall see him as he is" (1 John 3:2).
Not if. When. And note the mechanism again, right at the end: we shall be like him because we shall see him.
The same way it works now, only without the veil.
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Objections you will actually hear
“I keep committing the same sin. I must not really be saved.”
Paul describes exactly this in the first person: "I do not do what I want, but I do the very thing I hate" (Romans 7:15). Whether he writes of his pre-Christian or Christian experience is debated, but Galatians 5:17 is unambiguously about believers: the flesh and the Spirit are "opposed to each other, to keep you from doing the things you want to do". Ongoing struggle is evidence that there are now two parties in the fight. A person with no conflict has one.
“Some teach that you can reach sinless perfection in this life.”
Scripture rules it out directly: "if we say we have no sin, we deceive ourselves" (1 John 1:8), and Paul, near the end of his life, says "not that I have already obtained this or am already perfect" (Philippians 3:12). The goal is real and pursued seriously; its completion is at glorification, "when he appears we shall be like him" (1 John 3:2). Teaching that promises it now produces either despair in the honest or self-deception in the rest.
“If I am already accepted, why bother trying?”
Because the motive has changed, not disappeared. You are not working to be accepted; you are working because you are. Paul makes God's prior work the reason for effort: "work out your own salvation... for it is God who works in you" (Philippians 2:12-13). A child does not do chores to join the family. Doing them because they belong is a better motive, not a weaker one.
Watch
Chosen because each one gives you something the text cannot — a scholar’s own voice, a live exchange, a map, or a face.
The verses about counting the cost, preached without softening. A necessary corrective to any presentation of the gospel that promises only benefits.
Watch on YouTube · Preacher TalksThe step almost everyone skips: the Great Commission says make disciples, not converts. This is what happens after someone says yes.
Watch on YouTube · RadicalPut it into practice
- 1Name one specific sin and one specific means of grace you will use against it this week. Vague resolve fails.
- 2Read 2 Corinthians 3:18 and note the mechanism: beholding, then transformation. Not the reverse.
- 3Tell one trustworthy Christian the thing you would least like to say out loud. Secrecy is where sin does its work.
Terms used here
- SanctificationLatin: sanctus — holy
- The lifelong process of a Christian actually becoming like Christ.
- Mortification of sin
- The deliberate putting to death of remaining sin in a believer.
- HolinessHebrew: קָדוֹשׁ (qadosh) — set apart
- God's otherness — being in a category of one — and only then his moral purity.
- Glorification
- The final removal of sin and the resurrection of the body.
Go deeper
- BookThe Mortification of Sin — John Owen
Seventeenth century, demanding, unmatched on how sin is actually killed. Read a modern-English edition.
- BookThe Pursuit of Holiness — Jerry Bridges
The most accessible modern treatment.
- BookYou Are What You Love — James K. A. Smith
On habits and desire — why information alone rarely changes anyone.
Part of these study tracks
Read next
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What it means to be saved, from what, by whom, and how it is received — the whole doctrine traced from the problem in Genesis to the outcome in Revelation.
Pneumatology — the doctrine of the Holy Spirit
Who the Holy Spirit is, what he does, how to walk in step with him, and where Christians differ on the gifts — the most neglected person of the Trinity, treated seriously.
Prayer — what it is, how it works, and what to do when it does not
A practical and biblical account of prayer: the pattern Jesus taught, why unanswered prayer is not a system failure, and how to build a habit that survives dry seasons.
Grace and works — resolving Paul and James
The apparent contradiction between "justified by faith apart from works" and "faith without works is dead" — and why the two writers are answering opposite errors.
Ask the Harvest assistant anything on this topic. It answers from Scripture, cites its references, and will tell you where Christians honestly disagree.
Ask about TheologySpotted a mistake — a wrong verse, date or name, or a view stated unfairly?Report it