Who was the first in Scripture to teach explicitly about the sin nature?
Paul is the first in Scripture to teach explicitly about the sin nature. He teaches that with the cross this whole idea appears for the first time: the sin nature can be crucified by faith, committed to God, declared dead, and replaced by a new divine nature.
Les explains that once the cross comes, Paul is the one who teaches explicitly for the first time in Scripture about the whole idea of a sin nature. According to the context, this sin nature can be crucified and by faith committed unto God, to have Him put it to death. The old sin nature has to be declared dead, at least so far as God is concerned, although it remains a viable force in our living. When God reckons old Adam as crucified, He puts within us a new nature, a divine nature, the very mind and nature of Christ Himself, which is what it means to become Christlike or Christian. But even though God reckons old Adam as dead and sees him no more—justification being as if we have never sinned—in our experience as a believer, old Adam is still there. The only hope is that God has intervened with something that will help us control this old Adam and keep him defeated.