I disagree with you. I believe that it contains a specific teaching that is distinct from the whole of the eight chapters that you are referring to.
If you make a doctrine out of 4 or 5 alone, you can easily make a false doctrine. But if you see the context of 6, that PREVENTS the false teaching. See why it is dangerous to think chapter 4 is distinct?
Romans 4: justification without the law.
Romans 5: not under law, but under grace.
Romans 6:
- 1 What shall we say then? Are we to continue in sin so that grace may increase? 2 May it never be! How shall we who died to sin still live in it?
- 15 What then? Shall we sin because we are not under law but under grace? May it never be! 16 Do you not know that when you present yourselves to someone as slaves for obedience, you are slaves of the one whom you obey, either of sin resulting in death, or of obedience resulting in righteousness?