Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ, through whom also we have obtained our introduction by faith into this grace in which we stand; and we exult in hope of the glory of God.
Romans 5:1-2 ~~ Justification gives us "peace with God," "grace in which we stand," and "hope of the glory of God." These seem to conform to the theological distinctions of imputed righteousness (right-standing before the seat of judgment), imparted righteousness (ongoing sanctification by grace through works), and divine filiation (participation in Christ's nature and glorification as sons of God).
Romans 5:2-5 ~~ Not only do we exult in hope for glorification, but we also "exult in our tribulations" --that is, our ongoing purification -- "knowing that tribulation brings about perseverance; and perseverance [brings about] proven character; and proven character [brings about] hope; and hope does not disappoint...." Because God has already poured out His love, we can rely on Him in hope of glorification (v. 2).
Romans 5:7 ~~ This verses relies on the distinction between "righteousness" and goodness introduced in Romans 4:4-5. Righteousness arises from faith; goodness is more associated with works ("to one who works, his wage is not credited as a favor, but as what is due." This is why God's love is demonstrated in His grace to sinners, just as our obedience to the law of Moses is better encapsulated in our treatment of enemies than our treatment of neighbors (Matthew 5:44).
Romans 5:8-10 ~~ Romans 5:8 is one of the better known verses in the Pauline epistles. However, look at how Paul applies it. If God loved us so greatly "while we were still sinners," how much more will He preserve us "having been reconciled" to Him? This passage implicitly contrasts our former status as sinners with our new status as regenerate creatures; that is, as sons of God. As such, it seems to contradict the Lutheran dictum simul justus et peccator: "both justified and a sinner."
Romans 5:10-11 ~~ "...we shall be saved by His life. But not only this, but also exulting in God through our Lord Jesus Christ, through whom we have now received the reconciliation." We can rejoice not only in our preservation from death, but also in the promise of our full sonship.
Romans 5:12-19 ~~ Here is an extended section contrasting Adam and Jesus Christ, both as moments in salvation history ("as through the one's man's disobedience the many were made sinners, even so through the obedience of the One the many will be made righteous") and as typologies ("Adam, who is a type of Him who was to come..."). The first Man, Adam, was created in the image and likeness of God. Jesus was eternally begotten of the Father and born of the immaculate Virgin, in the perfect likeness of God and therefore in the true form of Man.
Romans 5:13 ~~ This verse is an important corollary to the Romans 2:12 and 4:15 passages on the connection between human knowledge and divine judgment. "For until the Law sin was in the world, but sin is not imputed when there is no Law." We still suffered its effects of sin under the curse (e.g., "death reigned from Adam until Moses") but prior to the Law we were immune from its imputation as violation of Law.
Romans 5:14 ~~ Death is the natural consequence of sin as separation from God, not necessarily as transgression against the known will of God (i.e., sin "in the likeness of the offense of Adam"). That subordinate clause is particularly notable: "death reigned... ever over those who had not sinned in the likeness of the offense of Adam." This passage could be taken in a number of ways -- for instance, as referring to children prior to the age of accountability -- but the first implication should be clear: not all sins are equal (cf. 1 John 5:16-17).
Romans 5:15 ~~ A typological contrast between Adam's rebellion ("by the transgresison of the one, the many died") and Christ's obedience ("the gift by the grace of the one Man... abound to many"). This is repeated in Romans 5:18-19.
Romans 5:16 ~~ "On the one hand the judgment arose from one transgression resulting in condemnation, but on the other hand the free gift arose from many transgressions resulting in justification."
Romans 5:20-21 ~~ God gave us the Law to increase transgression (purpose implied by the conjunction "so that"). But this increase in transgression corresponds to a parallel abundance in grace. "As sin reigned in death, even so grace would reign through righteousness to eternal life through Jesus Christ our Lord."
The bulk of Romans 5 is Christological, particularly with reference to the Adamic typology. (That last sentence might be a mouthful, but it was also really fun to say!) The initial verses are a continuation of the Romans 4 passage on justification. Even so, these verses seem to emphasize the hope of glorification over the initial moment of conversion, the realization of justification, or the ongoing work of sanctification (though the hope of glory is framed in the context of tribulation and purification). The latter verses focus much more particularly on the work of Christ in the context of His prefiguration and antithesis, Adam. Paul reserves his fiery denunciation of the antinomian heresy for the beginning of Romans 6, but in these verses he seems quite close to the Augustinian notion of felix culpa. This teaching may be best understood in the words of the Exsultet of the Easter Vigil: "O happy fault, that gained for us so great a Redeemer."
O certe necessárium Adæ peccátum,
quod Christi morte delétum est!
O felix culpa,
quæ talem ac tantum méruit habére Redemptórem!