“Self” may refer to the believer’s regenerated spirit–the new self.
When a person is redeemed through faith in Christ he/she is regenerated. This essentially relates to one’s human spirit being born again and made alive to God (John 3:3; Titus 3:6).
Colossians 3:10 declares that God’s children “have put on the new self who is being renewed to a true knowledge according to the image of the One who created him” (NASB). Similarly, in Ephesians 4:24 we are exhorted speak and behave in a way that corresponds to our new spiritual nature: “and put on the new self, which in the likeness of God has been created in righteousness and holiness of the truth” (NASB). Notice the past tense of the verb. At conversion, the believer has put off the old self (the “old man” – Rom. 6:6) and has put on the new self (literally “new man”). Through the miracle of salvation, we are united to Christ spiritually (1 Cor. 6:17) and are recreated at the core of our personhood. “Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new [spiritually]” (2 Cor. 5:17).
When we appreciate how our essential self is united with Christ, made holy and blameless, we can lift our hearts in worship due to God’s marvelous grace. “If then you were raised with Christ, seek those things which are above, where Christ is, sitting at the right hand of God. Set your mind on things above, not on things on the earth. For you died [the old man/old self], and your life [your new spiritual self] is hidden with Christ in God. When Christ who is our life appears, then you also will appear with Him in glory” (Col. 3:1-4).
Therefore, have a “white funeral” for your old self and appropriate by faith your identification with Christ in His death, burial, resurrection, and ascension (Rom. 6:3-14). Take up your cross daily, saying “no” to the old programming (the flesh) and “yes” to the indwelling Christ and the new divine nature of which you are a partaker (Luke 9:23; Titus 2:11-14). Accept your worth and dignity as a redeemed, made-in-God’s-image person. Give thanks for your new, positive, unshakeable spiritual identity. Abide in Christ as your ultimate resource for living.
To compare this with the other three uses of “self” in the New Testament, see the article: “Sorting_Your Self_Out”