God made mankind, male and female, in his image and gave them dominion and power. But Adam and Eve sinned. They and the earth were cursed. But Christ has come, and in his resurrection power as the second Adam, brings renewal and restoration. As you trust him, you are created anew, as Paul tells you in Ephesians 4:17–24.
Do not walk as the Gentiles do. They live in ignorance of God. You are the body of Christ. Paul insists that you live that way. You may no longer walk (and the theme of walking runs through the passage) or live as the pagan Gentiles do. Their thinking is alienated from God. They live in spiritual darkness–because of the hardness of their hearts. They are separate from God. The ignorance is not an excuse — sinful man willfully cuts himself off from God and God’s self-revelation, see Romans 1.
Idolatry leads to immorality. Having a false god leads to sinning against the true God. Romans 1:24–31 describes the immorality of the Gentiles as God’s judgment. He gives them over. Here Paul describes a similar pattern from a human perspective: they have given themselves over. There is a close relationship between our theology (whether we are conscious of it or not) and our practice, the way we live. Paul pictures a deepening spiral, a whirlpool of sinfulness, which sucks down those who venture in. Paul has a realistic awareness of the enslaving power of sin. Don’t toy with it!
Instead, put off the old. Your old self has died. Is the Christian, this side of heaven, an old self and a new self, both living together in a state of tension? Some see it that way. That leads to blaming what one does on the old self, and even to theological formulation in which someone is saved, but self or the old man is still on the throne. Ephesians 4, taken alone, might be read that way–put off the old self, put on the new. But that doesn’t fit with the way that Paul describes the situation elsewhere, see Romans 6; Colossians 3:3, 9, 10. Paul pictures the old self as having died, as having been buried with Christ. We are now new.
“[Christ] is invested with and is the embodiment of resurrection power. And since believers have been raised with him, they live in the abiding power, virtue, and grace of Jesus’ resurrection life; they walk in newness of life (Romans 6:4).”
John Murray, Principles of Conduct, p. 221
Therefore, get rid of what is old. Recognize the things in your life which are characterized by sin, by the old self, and get rid of them. Throw them out. Be about the business of the slaughter house (John Murray). Be honest about your motivations. Be discerning about what you allow into your brain and heart. Only because the old self is dead can you make these changes. Recognize that sin contradicts what you are in Christ.
Positively, live as the new creation that you are. You have come to learn Christ. Christ is not just someone that you learn about, though you certainly do need to know some things about him. You need to learn him. You need to be his disciple, to follow, to listen, to put what you hear into practice. The sin that you are to put off is an utter contradiction of the risen, glorified Christ. And you have been united with him.
“Now in Scripture the act by which the Holy Spirit causes us to understand the word of Christ in its spiritual sense and content and opens our consciousness to the truth is called by the particular term ‘enlightenment.’ Since sin has darkened the mind (Rom. 1:21; 1 Cor. 1:21; 2:14; Eph. 4:18; 5:8), what is needed is a renewal of the mind (Rom. 12:2; Eph. 4:23). This renewal is accomplished by God, who by revelation takes away from a person the hindrance that up until that time blocked the true understanding of things…. He does this by bestowing the Holy Spirit….”
Herman Bavinck, Reformed Dogmatics, Vol. 4, page 99
That means, put on what has been re-created in God’s image. The first Adam had been made in God’s image, and reflected that in the way he lived. But he sinned, and death, despair, helplessness, and bondage entered this world. Appropriately the second Adam has been raised. In him the enslaving power of sin has been broken. You, if you are united to Christ by faith, now can and must live to God’s glory. God’s creative power is no less present as he changes your sinful habits that it was when he spoke the universe into place. Just as Adam was made in God’s image, you have been re-made in that image. And you do reflect God’s holiness and glory. This transformation affects your life as a believer. But it also gives hope as you do the work restored to you–that of subduing and ruling the world to God’s glory.
Made in the image of God — that’s what you are. But even more, you have been re-made, re-created in God’s image and to his glory. Live as one who is truly alive in Christ.