As mentioned previously, I'm reading through the Pauline epistles and am currently in Romans. This isn't exhaustive reading/study, I'm just doing a surface reading working through a chunk of verses in the Greek each morning.

Today was Ro 6.15-23. And it was v. 19 that jumped out at me, again due to structure/repetition of phrases in the verse. Here is the Greek. The indentation is to line up repetitions; it is not necessarily indicative of any syntactic phenomenon in the sentence.

ὥσπερ γὰρ
   παρεστήσατε τὰ μέλη ὑμῶν δοῦλα
      τῇ ἀκαθαρσίᾳ καὶ τῇ ἀνομίᾳ εἰς τὴν ἀνομίαν,

οὕτως νῦν
   παραστήσατε τὰ μέλη ὑμῶν δοῦλα
      τῇ δικαιοσύνῃ εἰς ἁγιασμόν.

The bold phrase is almost exactly alike in both instances; the only difference is the mood of the verb. In the first instance, it is an aorist active indicative; in the second it is an aorist active imperative. The pattern in the phrases following the bold phrases is also the same: [dative noun(s)] + εἰς + [accusative prepositional object]. Here's the English of the ESV with respective portions bolded:

For just as
   you once presented your members as slaves
      to impurity and to lawlessness leading to more lawlessness,

so now
   present your members as slaves
      to righteousness leading to sanctification.

We can see the difference between the aorist indicative ("you (once) presented") and the aorist imperative ("present"). We can also see that εἰς + accusative was (in the ESV) translated as "leading to".

In the past, says Paul, we "presented our members as slaves" to "impurity and lawlessness", which led to "more lawlessness". This is weird language to us today; it means essentially that prior to knowledge of our salvation in Christ, we pursued sin, and as we did this we were drawn into deeper into sin. It's a nasty circle, spiraling downward. Our fallen nature (what I'd call "sin") is evidenced by these impure and lawless acts (what I'd call "sins").

Paul says "Stop it!"

Now that we know that God has saved us through Jesus Christ, we have to stop "presenting our members as slaves to sin" and do the opposite. Instead of pursuing sin, we must instead pursue righteousness. Paul earlier (cf Ro 6.5-14) writes that our "old self" was "crucified along with [Christ Jesus]" so that we'd "no longer be enslaved to sin". That was then, this is now. Paul says, basically, "You used to do that, now do this." He's telling us to change our action. He's telling us to stop sinning and instead start obeying, start doing what God commands. We're no longer bound to sin, so there's no reason to serve it. We need to change our action to reflect our allegiance to a new master.

The choice is clear; the pattern/structure of the text used by Paul here makes it even clearer. He's comparing two alternatives: One leads to impurity and compouding lawlessness; the other leads to righteousness and eventual sanctification. He recommends and commands the alternative he has chosen when confronted with the same choice -- righteousness leading to sanctification. This is pursued by becoming subject to righteousness, or (in English) stopping our sinful actions and starting to act in obedience to the will of God.

Is this easy? No. Will it happen overnight? No. But that doesn't mean that we don't try. That doesn't mean that we don't fight the battle and try to do our best to follow Him, despite the sinful fallen nature that we must daily contend with. Paul will discuss this later (cf. Ro 7.14-25). Paul knows this is a tall order because he knows that he can't live perfectly under the law. He needed Jesus too.

Update (2005-07-01): Responding to comments from Geoff Hudson, I should say that I don't see any reason to propose a redacted text here. I also don't see any evidence that Romans was originally a "Jewish document" that was later re-worked (redacted) for some reason, and that we have the re-worked (redacted) form and not the original. Geoff is, of course, free to consider and look into a redaction thesis such as this. I just don't think it is tenable and it requires today's reader to make a whole lot of unsubstantiated assumptions regarding the text; then it requires one to read those assumptions back into the text in order to make it work. From my perspective, that sort of approach is improper.