In Christian salvation sin is not removed from the ‘old man’ but remains and the deeds of the flesh are mortified. The ‘old man’ is your body that is visible. Your soul is invisible. Your ‘old man’ was made from the dust of the ground [Genesis 2:7] and is what contains the rest of your being. Paul refers to the ‘old man’ as clay [Romans 9:21; see also Job 10:9; 33:6] and vessels [Romans 9:22-23; 2 Cor 4:7; 2 Tim 2:20; Hebrews 9:21; Rev. 2:27].
Imagine what you see in the mirror as a vessel that contains your soul and spirit. What you see if a covering but it doesn’t have any life within itself but reflects the life and nature of your soul. That means that when your soul sins the sin is manifest in your ‘old man’ and becomes a ‘work of the flesh’ [Galatians 5:19-21]. This is why Jesus speaks of sin ‘coming from within a man’ [Mark 7:21-23] and why one of his basic messages is that even when you think about sinning you are guilty of committing sin.
Paul talks about sin making him do what he doesn’t want to do in Romans 7:17-20, “17 So now, no longer am I the one doing it, but sin which dwells in me. For I know that nothing good dwells in me, that is, in my flesh; for the willing is present in me, but the doing of the good is not. For the good that I want, I do not do, but I practice the very evil that I do not want. But if I am doing the very thing I do not want, I am no longer the one doing it, but sin which dwells in me.”
Where does the sin dwell? In the ‘old man’. This is why Paul urges Christians [Romans 6:12-19] to not submit their bodies to unrighteous deeds because it will stimulate the sin within the ‘old man’.
Finally in Romans 8:13 Paul says how to stop the work of sin within the ‘old man’ and that is by the Holy Spirit. In fact Christians simply ask the Holy Spirit to mortify the sin within the ‘old man’ or mortify the ‘works of the flesh’. Paradoxically it was sinful man who crucified Jesus on the cross and now it’s the Holy Spirit that crucifies or brings death to sinful men.
So you see sin is never eradicated from the ‘old man’ just mortified by the Spirit and Christians are exhorted to not take part in activities that stimulate sin within the ‘old man’. You have to figure out, for instance, what makes you angry, since anger is a work of the flesh, and stop the activity that leads to your anger. If watching TV stimulates your ‘old man’ to anger then stop watching TV. There is a cause and effect of works of the flesh once you are born again and it is your responsibility to figure out what you do that causes the works of the flesh and stop doing those activities.
Of course sin leads to a work of the flesh and the Ten Commandments are the best place to identify specific categories of sin like idolatry but you have to calculate what you specifically do that is idolatrous and stop doing it.
The point today is that sin remains in the ‘old man’ in Christian salvation. The goal is not to convert the ‘old man’ but to mortify it by the work and power of the Holy Spirit.