If we boil the Christian life down to simply killing sin, we rob ourselves of the deepest hope and highest joys.

Yes, every true Christian will be killing sin. Any other version or distortion of Christianity falls short of what Christ died for. “Put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires” (Ephesians 4:22). “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). If we do not kill sin, we will die in our sin. But if we wage war against our sin, in the power of the Spirit, we prove that Christ is alive in us, and that we will never die.

Killing sin is essential to the Christian life, but it’s not the essence of the Christian life. When Christ calls us to deny ourselves, take up our cross daily, and follow him — and he does summon us to deny ourselves — he does so that we “may have life and have it abundantly” (John 10:10). What we put on is far greater than anything we put off or leave behind.

The New You

God has given us hit lists of sins to kill. For instance, Colossians 3:5, 8–9: “Put to death what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry. . . . Put them all away: anger, wrath, malice, slander, and obscene talk from your mouth. Do not lie to one another, seeing that you have put off the old self with its practices.”

We cannot follow Christ without putting off something, but that doesn’t mean following Christ is only about what we put off.

Just keep reading in Colossians 3, next verse: “ . . . and have put on the new self, which is being renewed in knowledge after the image of its creator” (Colossians 3:10). You have not only put off your old self. You have put on a new self. And your new self looks more and more like the one who created and sustains every corner of the universe. As horrible as we looked in our sin where God found us, we are now being rebuilt and refined in his spectacular image.

We find similar language in 2 Corinthians 4:16: “Though our outer self is wasting away, our inner self is being renewed day by day.” We are being made into the image of an infinitely big, perfectly holy God. That process happens painstakingly slow — one day at a time — from one precious degree of glory to another (2 Corinthians 3:18).

The Power of Knowing God

But how are we being changed? “[You] have put on the new self, which is being renewed in knowledge after the image of its creator.” What does it mean to be renewed “in knowledge”?

This is not the first mention of “knowledge” in Colossians,

We have not ceased to pray for you, asking that you may be filled with the knowledge of his will in all spiritual wisdom and understanding, so as to walk in a manner worthy of the Lord, fully pleasing to him: bearing fruit in every good work and increasing in the knowledge of God. (Colossians 1:9–10)

Putting on the new man is not something first we do, but something we know — and in particular, someone we know. Notice how knowledge is the beginning and end of this kind of spiritual growth. Knowledge equips us to walk in a manner worthy of the Lord — “so as to walk . . . ” — and we walk in a manner worthy of the Lord because we want to know him more — “increasing in the knowledge of God.”

Christian maturity is not only marked by sins that have been put to death, but by a deeper personal knowledge of and intimacy with God, and a deeper commitment to his people, the church (Ephesians 4:13). Yes, sexual immorality, anger, and deceit are being put off. But something breathtaking is being put on in their place: love. Again, Paul prays, “It is my prayer that your love may abound more and more, with knowledge and all discernment” (Philippians 1:9).

Put on What?

As we deepen our knowledge of God, in relationship with him, we discover new aspects and expressions of this new self. What does the new you look like? “Put on then, as God’s chosen ones, holy and beloved, compassionate hearts, kindness, humility, meekness, and patience” (Colossians 3:12). Forgiveness (Colossians 3:13). Peace and gratitude (Colossians 3:15). “And above all these put on love” (Colossians 3:14).

The new you is not defined mainly by what you have put off — by the sins you have put to death — but by the evidence that Christ is living in you by his Spirit. As Christians, we are not defined by what we say no to, but by whom we finally say yes. People will notice that we abstain from sexual immorality, and may even ask why. But Paul says, “If I give away all I have, and if I deliver up my body to be burned, but have not love, I gain nothing” (1 Corinthians 13:3). And Jesus says, “By this all people will know that you are my disciples, if you have love for one another” (John 13:35).

You can avoid pornography completely, refrain from ever boiling in anger, never cheat on your taxes, and still hate Jesus. But you cannot experience the compassion, humility, peace, joy, and love that only comes to those who love him.

Sin Is Gone, Joy Has Come

If you hear the summons to “put on the new self, which is being renewed in knowledge after the image of its creator” (Colossians 3:10) and only grumble over what you have to give up or grieve over remaining sin in your life, you haven’t heard the beauty of what Paul is saying. If you have made war against sin, you are now being made into someone new and better. The Spirit is not only empowering you to say “No” where you’ve said “Yes” a thousand times before. He is also empowering you to say “Yes” in ways you’ve never been able to before.

As you put on your new self, walking in a manner worthy of the Lord, you are “being strengthened with all power, according to his glorious might, for all endurance and patience with joy” (Colossians 1:11). Yes, we deny ourselves when temptation comes. Yes, we grieve whatever sin remains in us. But we deny and grieve, live and endure with joy. People stop committing sins for all kinds of reasons, but no one enjoys Jesus without God’s help — without God making us entirely new.

Put off whatever remains of the old you, but don’t stop just at killing sin. “We are [God’s] workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them” (Ephesians 2:10). Put on, by the power of his Spirit, what no one else in the world can have any other way. God gave us new life in Christ not just to say no to sin, but to say yes to a thousand other things, in love.