Aaron.
you said: if the “new self” referred to a perfectly sinless nature we already possessed, we wouldn’t have to be exhorted to “put off the old self” and to “put on” the new one. To “put on the new self” is simply to live worthy of one’s calling as a believer by continuing to renew the spirit of one’s mind (btw, if one’s spirit were “perfect” it wouldn’t need renewing). Paul isn’t talking about sinless perfection here - which is what having a sinless nature would make us.
Born Again: The “old self” is the remnant of the soul and the flesh that are not redeemed that remember the sin you once committed, especially the flesh. Why do you think we must renew our minds with the word of God, prayer, etc? It is not the spirit that needs renewing ( that was renewed when you were born again) but the soul ( mind, will, emotions) and your flesh. You do have a sinless nature, rather you know it or not ( your reborn spirit).That is if you are born again.
Born Again believers have the ability not to sin because after we are born again…we no longer have a sinful nature or spiritual death nature in our bodies. Romans 8:2 " For the law of the Spirit of life in Christ Jesus has set you free from the law of sin and of death. Romans 6:6-7 " Knowing this, that our old man( old sinful nature) is crucified with him, that the body of sin might be destroyed(old sinful nature destroyed), that we no longer be slaves to sin; for he who has died is freed from sin."
Aaron, do this discussion a favor and respond to my topic "Are you Born Again. What does it mean? "