Notes & Commentary:
Ver. 1. The apostle proceeds in this chapter to shew how great a benefit it is to be truly justified by the coming of Christ. — Let us have  peace with God. That is, says St. Chrysostom, by laying aside all contentions. Or let us have peace with God by sinning no more. And this peace we may have under the greatest tribulations, which conduce to our greater good, to an increase in virtues, in patience, in hope, in the love of God, &c. (Witham)
Ver. 3. We glory in spirit in the afflictions, oppression, and persecution, which we suffer as Christians, esteeming them a great blessing. Thus the apostles went rejoicing from before the council, because they had been thought worthy to suffer disgrace for the name of Jesus. (Acts v.) And St. James (chap. i.) says: Think it the greatest joy when you fall into various temptations: (i.e. tribulations) for these sufferings greatly serve to confirm the elect in the hopes which they have of enjoying the glory of the world to come. (Estius)
Ver. 5. God having prevented us with his gifts when we did not at all deserve them, having showered upon us the blessings of faith, charity, patience, and fidelity, we cannot but have the greatest confidence that after this pledge and assurance of his good will towards us, he well finish the work he has begun, and bring us to his heavenly kingdom. (Calmet) — Not only the gift of the Holy Spirit, but the Spirit himself, is given to us, who resides in our soul as in his own temple, who sanctifies it, and makes it partaker of his divine love. (Menochius)
Ver. 6. &c. Why did Christ…die for the ungodly? He shews Christ’s great mercy and love for mankind, that he would die for us, who were sinners, and consequently his enemies. How few are there that will lay down their lives for a just man, or for a just cause? — Perhaps for a good man. That is, for another, who has been good to him, his friend or benefactor, we may find one that will expose or lay down his life. But Christ, in due time, appointed by the divine decree, died for sinners, for us all. And if we have been reconciled to God, and justified by his death; now being made the children of God, and his friends, we may with greater confidence hope to be saved. (Witham) — The text of the Greek is as follows: For when we were weak, he gave us our Lord Jesus Christ to redeem us; shewing how much God loved us, to perform such stupendous acts of love in our behalf. But the reading of the Vulgate is conformable to St. Irenĉus, (lib. iii. chap. 18.) and to the commentaries of this epistle, which have been published under the name of St. Ambrose, and St. Jerome. (Calmet) — St. Augustine says, those whom the apostle first calls weak, he afterwards calls impious, hos dixit infirmos quos impios. (Ep. lix. ad Paulinum.) — St. Jerome, and other fathers and commentators, explain the Greek text of this verse as follows: Scarcely would any one die for a just cause; for who would ever think of dying in defence of injustice? Others explain it thus: Scarcely a single man would die for one that was wicked and unjust: for we can hardly find a person ready to lay down his life for a good man; his friend and benefactor, who has been kind to him. (Calmet)
Ver. 12. As by one man…in whom  all have sinned. That is, in which man all sinned, (not in which death all sinned) as it must be the construction by the Greek text: so that these words are a clear proof of original sin against the Pelagian heretics, as St. Augustine often brings them. Nor does St. Chrysostom deny original sin, though in this place he expounds it that all by Adam’s sin were made guilty of death and punishments. But how could they deserve these, had they not sinned in Adam? (Witham)
Ver. 13-14. Until the law, sin was in the world. That is, from Adam’s fall, both original sin and actual sins truly infected all mankind. (Witham) — Not imputed. That is, men knew not, or made no account of sin; neither was it imputed to them, in the manner it was afterwards, when they transgressed the known written law of God. (Challoner) — All were conceived and born in sin, in what we call original sin, and liable to death, even infants, who were not come to the use of reason, and consequently could not sin after the similitude of the transgression of Adam, or by imitating his sin, but were born in sin: and besides this, all manner of actual sins, which men committed by their own perverse will, reigned every where in the world. But before the law these sins were not imputed, that is, were not declared sins, that deserved such punishments as were ordained by the law. — Adam, who is a figure of him that was to come. That is, of Christ, whom the apostle calls the last Adam, 1 Corinthians xv. 45. But he was a figure by contraries. By the first Adam, sin and death entered into the world; by Christ, justice and life. (Witham)
Ver. 15. &c. But not as the offence, so also is the gift, or the benefits which mankind receive by their Redeemer, Jesus Christ. For St. Paul here shews that the graces which Christ came to bestow upon men, and offers to all, are much greater than the evils which the sin of one man, Adam, caused. 1. Because, if by the offence of that one man, Adam, many, i.e. all died by original sin that descended from Adam, (the blessed Virgin mother by a special privilege being always excepted) much more the grace of one man, Jesus Christ, hath abounded unto many, the comparison does not imply that more in number receive the grace of Christ, than were infected with sin; but that they who receive the graces which are offered to all, receive greater benefits than were the damages caused by the sin of Adam. For the judgment indeed was by one unto condemnation, or so as to make all guilty of one sin, that is, of original sin; and for other actual sins, men committed them by their own proper will; whereas the grace of Christ justifies men from many sins; that is, also from all sins which they have committed by their own malice. 2. Because by it, that is, by the offence of one man, death reigned in the world, and made all men liable to damnation; yet now by the incarnation of Christ, (which would not have been, had not Adam sinned) all they who are justified by the grace of their Redeemer, have Christ God and man for their head: he is become the head of that same mystical body which is his Church: they are exalted to the dignity of being the brothers of Christ, the Son of God; they are made joint heirs with him of the kingdom of heaven, and so by the grace of Christ have a greater dignity in this world, and shall be exalted to a greater and more eminent degree of glory in the kingdom of his glory for all eternity; which hath given occasion to the Church, in her liturgy, to cry out, as it were with a transport of joy, O happy fault, which hath procured us such and so great a Redeemer! See St. Chrysostom, hom. x. (Witham)
Ver. 20-21. Now the law entered in. Not that the law was designed for that end; but the word that, as in many other places, so here expresseth only the consequence that followed, when sinners occasionally became more guilty by the knowledge of the law, and the precepts given. St. Chrysostom takes notice that it is not said the law was given, but only that it entered in, as it were by the by, and only for a certain time, till our happy redemption, reconciliation, and justification by Jesus Christ. (Witham) — That sin might abound. Not as if the law were given purposely for sin to abound; but that it so happened, through man’s perversity, taking occasion of sinning more, from the prohibition of sin. (Challoner) — Where sin abounded. Grace abounded in the elect; for the apostle does not say that grace abounded in every place where iniquity had abounded; but he says indefinitely where, that is, in many places where sin abounded, grace hath abounded also. (Estius) — The Jews and Gentiles having become sensible of their weakness and misery, the Almighty, in his mercy, sent his only Son to enrich both the one and the other with his graces. The Gentiles were in the more deplorable case, and received the greatest abundance of grace; as may be seen from the great number of conversions wrought amongst them in so short a time in every part of the world. (Calmet) — In the Greek it is pareiselthe, entered in by stealth, as it were, and for a time, till the preaching of the gospel. (Menochius)
 Ver. 1. Pacem habeamus. In the common Greek copies we read echomen, habemus. But in other manuscripts echomen, as St. Chrysostom must have read by his commentary, meke amartanomen. &c.
 Ver. 12. In quo omnes peccaverunt, eph o pantes emarton. If it agreed with sin, in the Greek it must have been eph es.
 Ver. 15. Abundavit in plures; Greek eis tous pollous, in multos; so that it is not to be taken comparatively for more, but absolutely for many, or for all; because all here are many, as in other places.
 Ver. 19. See St. Chrysostom, hom. x. p. 73. Ed Savil. eis uiothesian echthemen … kai egenometha adelphoi tou monogenous, &c.
Bible Text & Cross-references:
The grounds we have for hope in Christ. Sin and death came by Adam: grace and life by Christ.
1 Therefore, being justified by faith, let us have peace with God, through our Lord Jesus Christ.
2 *By whom also we have access through faith into this grace, wherein we stand, and glory in the hope of the glory of the sons of God.
3 And not only so, but we glory also in tribulations: *knowing that tribulation worketh patience:
4 And patience trial, and trial hope;
5 *And hope confoundeth not: because the charity of God is poured out into our hearts, by the Holy Ghost, who is given to us.
6 For why did Christ, when as yet we were weak, according to the time, *die for the ungodly?
7 For scarce for a just man will one die: yet perhaps for a good man some one would venture to die.
8 But God commendeth his charity towards us; because when as yet we were sinners, according to the time,
9 Christ died for us: much more, therefore, being now justified by his blood, shall we be saved from wrath through him.
10 For if, when we were enemies, we were reconciled to God by the death of his Son: much more being reconciled, shall we be saved by his life.
11 And not only so: but also we glory in God, through our Lord Jesus Christ, by whom we have now received reconciliation.
12 Wherefore, as by one man sin entered into this world, and by sin death, and so death passed upon all men, in whom all have sinned.
13 For until the law, sin was in the world: but sin was not imputed, when the law was not.
14 But death reigned from Adam unto Moses, even over them that had not sinned after the similitude of the transgression of Adam, who is a figure of him that was to come.
15 But not as the offence, so also is the gift: for if by the offence of one, many have died: much more the grace of God, and the gift in the grace of one man, Jesus Christ, hath abounded unto many.
16 And not as it was by one sin, so also is the gift: for the judgment indeed was by one unto condemnation: but the grace is of many offences, unto justification.
17 For if by one man’s offence, death reigned through one: much more they who receive abundance of grace, and of the gift, and of justice, shall reign in life, through one, Jesus Christ.
18 Therefore, as by the offence of one, unto all men to condemnation: so also by the justice of one, unto all men unto justification of life.
19 *For as by the disobedience of one man, many were made sinners: so also by the obedience of one, many shall be made just.
20 Now the law entered in, that sin might abound. But where sin abounded, grace hath abounded more.
21 That as sin hath reigned unto death, so also grace might reign by justice, unto everlasting life, through Jesus Christ our Lord.
2: Ephesians ii. 18.
3: James i. 3.
5: Psalm xxii. 6.
6: Hebrews ix. 14.; 1 Peter iii. 18.
19: Philippians xi. 8. and 9.