How can the old sin nature be crucified?

Les explains that Paul teaches explicitly for the first time in Scripture about the sin nature, and that this sin nature can be crucified—literally 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. The minute God reckons old Adam as crucified, He puts within us a new nature, a divine nature, which is the very mind and nature of Christ Himself; that is what it means to become Christlike or Christian. Even though God reckons old Adam as dead, sees him no more, and justification is just as if we have never sinned, in the believer’s experience old Adam is still there. The only hope is that God has intervened with something that will help us control this old Adam, and we can keep him defeated.