18 Therefore, as one trespass led to condemnation for all men, so one act of righteousness leads to justification and life for all men.
In 18a Paul repeats the essence of his original idea of verse 12 and then completes it with a conclusion in 18b. In 5:18-19 Paul completes the contrasting consequences of the actions of Adam and Christ. Verse 18 states the outcome of verse 12.
In verse 18 Paul sets forth three more contrasts:
Verse 18 completes the contrast begun in verse 12 and restates verses 16 to 17.
Adam’s disobedience constituted mankind to be sinners, but Christ’s obedience constituted some people to be legally righteous (5:19).
There is a contrast between sin and super-abundant grace (5:20-21).
18 Therefore [literally—so then], as one trespass [Adam’s original sin] led to condemnation [punishment] for all men [all those Adam represented],
The “therefore” here brings us to the conclusion of the argument from verse 12. The one trespass of Adam led to judicial condemnation for all men. This is the judicial sentence of God whereby the federal headship of Adam led to condemnation of all due to his sin. Therefore, Adam’s one trespass constitutes all persons guilty sinners subject to eternal death and liable to eternal damnation. The ground of this judgment is the solidarity of the human family in Adam.
so one act of righteousness [Christ’s death on the cross] leads to justification [forensic or imparted] and life for all men [Jesus died provisionally for all and gives “life” to those who believe, not just the elect].
There is the idea of justification as status with God, but now we come to an advance on that justification —the justification of life. This justification allows us to enter fully into the life of Christ.
There is one action and one result. The one action is Christ’s death on the cross with the one result of a right standing before God and the life that comes with it. Jesus took the imputation of our sins on the cross and brought eternal life to all.
The second “all men” does not refer to every member of the human race; although Jesus died for all provisionally, only those who accept His provision of paying for sin will have eternal life. Here it means all believing men. “Life” here is eternal life. Eternal life comes from the One who has eternal life.
Representative union is a corollary of federal headship.
By Adam’s one transgression his original sin was imputed to all those he represented—the human race. By one act on the cross God imputed justification to all who believe. Both Adam and Christ are federal heads representing their constituencies joined with them in union. Adam’s single sin resulted in condemnation of all; Christ’s single sacrifice resulted in right standing before God forever.
God does not impute His righteousness to all men but only to those who embrace salvation provided in Christ.
The act of “one” man determines the destiny of everyone in his lineage en mass. Adam launched the death epoch and Christ launched the eternal life epoch. The second epoch has a gift character; it counters and cancels the old epoch.