Ephesians 4:21-24 (New Living Translation)
21 Since you have heard about Jesus and have learned the truth that comes from him, 22 throw off your old sinful nature and your former way of life, which is corrupted by lust and deception. 23 Instead, let the Spirit renew your thoughts and attitudes. 24 Put on your new nature, created to be like God—truly righteous and holy.
New Self via BibleStudyTools.com
Paul refers to the transformation that occurs at conversion as the creation of a new self. "Do not lie to each other, since you have taken off your old self with its practices and have put on the new self, which is being renewed in knowledge in the image of its Creator" ( Col 3:9-11 ). The Greek term for "new self, " neos anthropos [nevo"a [nqrwpo"], depicts an individual, male or female, who possesses a "new nature" or "new humanity." It characterizes a metamorphosis in conduct from a life of sin to one of righteousness and is equivalent in meaning to being born again. A parallel expression occurs in 2 Corinthians 5:17 where the individual is described as a "new creation."
The process of transformation into a new self is described by Paul in Ephesians 4:22-24 as involving three stages: (1) putting off the old self, which belongs to the former way of life; (2) being made new in the attitude of one's mind; and (3) putting on the new self. The words translated "put off" and "put on" in (1) and (3) are past tense in Greek, indicating a completed action (perhaps baptism). The word "made new" in (2) is present tense, indicating a continuing development of spiritual attitude.
In this process, the former self, which was given to the gratification of human desires, is put away (Col 3:8), stripped off like filthy clothes (v. 9). Baptism, unlike circumcision, which was the putting away of a mere piece of flesh, represented rather the stripping off of the whole body of flesh (v. 11). It s the entire former self that dies. Paul states in Romans that "our old self was crucified with him so that the body of sin might be done away with, that we should no longer be slaves to sin" (6:6).
Becoming a new person in Christ begins with the transformation of the mind. "Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind" (Rom 12:2). However, although the decision to become a Christian may be instantaneously made, the transformation of a sinful human body into one that exemplifies the conduct appropriate to the mind of the new self (righteousness and holiness, Eph 4:24) requires a lifetime of determination and discipline (Eph 4:22-5:21).
Peter writes: "Like newborn babies, crave pure spiritual milk, so that by it you may grow up in your salvation" (1 Peter 2:2). For Paul, the creation of the new self is the antithesis of the decay and death of the old self, the human body: "Though outwardly we are wasting away, yet inwardly we are being renewed day by day" (2 Cor 4:16).
This renewal is possible because the Spirit of God "helps us in our weakness" (Rom 8:26). "If the Spirit of him who raised Jesus from the dead is living in you, he who raised Christ from the dead will also give life to your mortal bodies through his Spirit, who lives in you" (Rom 8:11).