Ephesians 4:21–24 presents one of the clearest and most radical descriptions of the Christian transformation. Paul does not speak of an improvement, a gradual coexistence, or a partial correction of the old life, but of a complete separation between two identities: the old man and the new man.
If we have truly “heard Him and been taught by Him, as the truth is in Jesus,” then a decisive rupture must take place.
The old man is defined by deceitful lusts. These desires are not neutral weaknesses; they are corrupting forces that deceive the will, darken the understanding, and lead inevitably to sin. Paul does not say to manage them, tolerate them, or excuse them but to put them off. This is a once-for-all renunciation, a death sentence pronounced against the former way of life. The old man must not be negotiated with; he must be abandoned completely.
In contrast, the new man is not a theoretical position or a legal declaration only. He is created according to God, which means he reflects God’s character. Paul specifies this clearly: “in righteousness and true holiness.”
This holiness is not symbolic, not positional only, and not future-only. It is true holiness real, lived, practical holiness manifested in thoughts, intentions, words, behavior, and conduct. It is a holiness that does not coexist with sin. The new man does not occasionally return to the habits of the old man, because the two are incompatible.
To “put on the new man” therefore means to live from a new nature, governed by truth, ruled by righteousness, and characterized by holiness without sin. This new creation does not merely resist sin; he rejects it entirely. Deceitful lusts belong to the old man, not to the new. To return to them would be to deny the very reality of the new birth.
Paul also emphasizes the renewal of the mind. This renewal is not passive; it is the daily alignment of the will with the truth of Christ. As the mind is renewed, the conscience becomes sharper, the will firmer, and obedience becomes the natural expression of the new life. This renewal supports a life where sin is not normalized, excused, or expected, but decisively rejected.
Thus, true holiness and true righteousness are not optional ideals; they are the defining marks of the new man. A Christian who claims to have put on the new man while still living under the power of deceitful lusts contradicts Paul’s teaching. The gospel does not reform the old man it replaces him.
Ephesians 4:21–24 therefore affirms a foundational truth:
to be in Christ is to be separated from the old life and established in a new life of righteousness and holiness without sin.
This is not extremism; it is normal Christianity according to the truth that is in Jesus.