6 knowing this, that our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin.
7 For he who has died has been freed from sin.
8 Now if we died with Christ, we believe that we shall also live with Him,
9 knowing that Christ, having been raised from the dead, dies no more. Death no longer has dominion over Him.
body of sin (v.6) = power acting through the members of the body
done away with (v.6) — should be “rendered inactive” — because of our death with Christ, our bodies have been rendered inactive as instruments of sin. The source of sin is the will, but it uses the body as its instrument.
be slaves of (v.6) = bondage, slavery with no choice of kind or length of service
freed (v.7) = justified in the legal sense
There is no legitimate method of terminating sin’s claims except by death. Death both snaps all bonds and annuls all obligations. The statement of this verse [verse 7] covers the whole of the preceding argument and does not apply merely to the figure of bondage just mentioned. The special reference is to the subject of crucifixion, the death penalty which Christ endured. Our identification with Christ, as the One who endured the penalty for us, removes the legal sentence from us and thereby delivers us from a condition of bondage to sin. There is both the removal of the penalty and the deliverance from the power. A corpse can neither be punished nor can it become subservient to the will of another. — Vine, pg. 90
If (v.8) — inevitable result. Once we are saved, we live with Christ regardless of our own effort.
dominion(v.9) = power of a lord
Sanctification is not primarily a matter of striving to live holy, but of knowing that we are holy in Christ.
Paul’s way is always: doctrine first, then the application. We find this even within sections of his epistles [as in these four verses]. In the larger context it is the same. The “old man” has been crucified and buried with Christ; now accept this by faith and bury that “dead body” — experientially. We have this idea again in Colossians 3:9-10 and Ephesians 4:22, 24. The former passage states, “ye have put off the old man … and have put on the new man … ” while the latter exhorts, “… put off … the old man … and … put on the new man … ” The former refers to a positional fact, the latter to the practical application of that fact. — Stam, pg. 146-147)