What is the only remedy for the old Adam or old sin nature?
The only remedy for the old Adam, or old sin nature, is for God to move in by His omnipotent, all-powerful, omniscient power and put old Adam to death. This removes his power and influence so the believer can live with a new, divine nature.
Les explains from Romans chapter 3 that the old Adam cannot be remedied by human effort or improvement. The only remedy is for God Himself to move in, in His omnipotent, all-powerful, omniscient way, and put old Adam to death. This is so the believer is rid of the old Adam's power and influence and can get on with life with a new nature, a divine nature.