Why does Les replace the singular word "sin" with "old Adam" in Romans?
The singular word 'sin' in Romans refers to the old Adam, the Adamic sinful nature. It is the fountainhead of all problems. Replacing 'sin' with 'old Adam' clarifies that it denotes that nature, while plural 'sins' are the fruit or actions that old Adam causes.
Les explains that he uses the term 'old Adam' in place of the singular word 'sin' throughout the book of Romans because that is what it is really talking about. He reminds listeners that when Paul speaks of sin in the singular, it refers to that old Adam, who is the fountainhead of all our problems—the Adamic sinful nature. The fruit of old Adam are the things we do, which are sins plural. So sin singular usually refers to old Adam, while sins plural refers to the things old Adam causes us to do. In verse 3, God sent His own Son in the likeness of sinful flesh and for sin to take the place of that old Adam so that we could be crucified with Him, condemning old Adam in the flesh.
For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
More Questions
What are plural 'sins' in relation to the old Adam?
The plural word 'sins' refers to the fruit of the old Adam—the things that old Adam causes us to do.