I have been co-crucified with Christ; I live no more, but Christ lives in me; and the life I now live in the flesh I live by the Son of God’s faithfulness, the One loving me and giving Himself up on my behalf. (Galatians 2:20)
What is meant by a new self? A new self in Christ means a new understanding of and a new relationship to self, Christ, God, Holy Spirit, others and the world. Christ changes not merely the spiritual circumstances in which we live, but also our inner being or character – us. There in the depths of our heart, where we experience what we are and how we feel about ourselves, where our own self-image is often distorted and covered up by frustration and guilt, where God has nevertheless placed a treasure of spiritual gifts and powers, there is the where the personal identity of each human being is located and awaits an explosive release by the grace of Christ.
This same question of identity is as important to us as it was important to the man of the gospel account who was possessed by many demons. It is one of the key questions of life. But many are inclined to ignore it.
(Theodore Stylianopoulos, A Year of the Lord: Liturgical Bible Studies, p. 94)
Therefore, if any one is in Christ, he is a new creation; the old has passed away, behold, the new has come. (2 Corinthians 5:17)
Put off your old nature which belongs to your former manner of life and is corrupt through deceitful lusts, and be renewed in the spirit of your minds, and put on the new nature, created after the likeness of God in true righteousness and holiness. (Ephesians 4:22-24)