For quite some time I have wrestled with what 'the specifics' are that are floating in Paul's head as he inspirationally pens Romans 5-7. Is he still flushing out what is means to be justified? Is he now explaining results of justification: hope, assurance, etc.? Has he moved on to sanctification specifically? Is it some combination of these?
Recently I have come across some potential insight on Chapter 6 that I felt like sharing, either to edify you, the reader, or open myself up to correction and rebuke from you, the responder.
My observations begin from examining the phrase in 6:20 ~ "free in regard to righteousness." Because Paul's teaching on the unbeliever's (Jew or Gentile) relationship to “righteousness” is so clear in Ch.1-3, this phrase “free in regard to righteousness” may be very helpful at beginning to understand many other Pauline phrases (especially in the surrounding context): “set free from sin,” "slaves of sin, " and “slaves of righteousness.” Paul makes clear that, though people are not as bad as they could be, no one can live in righteousness as to obtain it's results: eternal life(2:6-7; 3:10,20). This is very possibly what he means by “you were free in regard to righteousness.” This might equate “free from sin” meaning that there is no way Christians could live in sin as to obtain it's results: death. Also, just as those who are “free in regard to righteousness” have 'more room' to be more wicked, those we are “free from sin” have more room to be more holy. Now, this understanding of “free in regard to righteousness” could indicate that “slaves of righteousness” means that Christians will undoubtedly obtain the outcome of righteousness: eternal life. Likewise, a “slave of sin” would undoubtedly obtain the outcome of sin: death.
However, even if all this has some validity, one cannot simply make these four statements about justification. The entirety of Ch. 6 demands that there are aspects in these phrases regarding the way one lives his/her life (6:4 “walk in newness of life” and 6:22 “set free from sin and have become slaves of God”), not just our legal standing before God.
Aha! It is very possible the inseparability of justification and sanctification (more or less the point of Ch.6 (6:1-2, 15)) is defended by Paul because he cannot find words to describe one (i.e. Being “free from sin” indicates we are unquestionably released from it's condemning power (justification)) without somehow describing the other at the same time (i.e. Being “free from sin” indicates that we are unquestionably released from it's appeal and attractiveness (sanctification)).
I can potentially see this same depth to the phrases "live in [sin]," "died to sin," "died with Christ," "live with him," "alive to God," etc. Verses 8:1-4 might be helpful to look at as well.
I need to let this marinate a little more. Maybe someone can help me do so. But wherever we land on this one, there are helpful reminders thrown in the middle of this chapter for us to end on:
1)6:19 ~ "I am speaking in human terms, because of your natural limitations [talking to Christians!]"
2)A combination of the commands in v.13 and 19 ~ "present yourselves [our responsibility] as instruments/slaves of righteousness" with the worship in v.17 ~ "Thanks be to God [credit given to God], that you who were once slaves of sin have become obedient from the heart..."