“Therefore, as one trespass led to condemnation for all men, so one act of righteousness leads to justification and life for all men. For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous.” -Romans 5:18–19
Paul, continuing his comparison, summarizes the federal work of the two Adams. The contrast between the one and the many in verse 19 is a concept rooted in ancient political theory. This is an important concept to understand in order to comprehend Paul’s argument. Some have by this passage misunderstood Paul to be teaching universalism. But to do so would be to impose modern democratic thinking on the ancient text.
The one is the monarch, the federal or seminal head of a people. The many are the people, those under the headship. The broader political treatment includes the few, the aristocrats or oligarchs, but is not treated here for obvious reasons.
To this end, the phrase Cuius regio, eius religio (literally, “whose realm, their religion” – the religion of the ruler was to dictate the religion of those ruled) held important meaning in the Middle Ages.
The first Adam trespassed (transgressed God’s law), an act that brought condemnation to all men under his federal headship (which in this case, is all men who were ever born, for all are born of the first Adam).
The second Adam obeyed the Father, even unto death (John 8:29), an act that brought justification and life to all men under his headship (those who believe).
We can now begin to think of all humanity being under one of the two federal headships—The headship fo the first Adam (to which all men are born) and the headship of the second Adam (to which only those who believe can be born).
Thus, Jesus told Nicodemus (John 3) that he must be born again.