“ ... and to put on the new self, created after the likeness of God in true righteousness and holiness.” Ephesians 4:24
The new self refers to the renovated nature. Like a house interior that’s been renovated. Same house new inside. The change is so great, that there is no impropriety in speaking of one who has experienced it as “a new person.” We has new feelings, principles, and desires. We have laid aside our old principles and practices, and, in everything that pertains to moral character, we are new.
This is not a small change. It is not a mere change of the outward condition. No, no new paint job or dry wall patch here. It’s not just being brought from the world into the church, and being baptized.
Our body is still the same; the intellectual structure of our mind is the same; but there has been a change in our principles and feelings which challenge us. The interior of our house has been completely redone.
God works in us through His Spirit to make us like Him.