12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned: (Romans 5:12 KJV)
William Burkitt’s Commentary
The doctrine of original sin is not more difficult to be understood than it is necessary to be known: the apostle here declares the manner how sin and death entered the world, namely, by the fall of Adam the first man: By one man sin entered into the world, and death by sin.
Note, 1. An unhappy parent; namely, Adam: By him sin entered into the world.
2. An unhappy posterity; namely, the whole world, proceeding from and coming out of the loins of Adam, in whom all have sinned.
3. An unhappy portion; sin and death: Sin entered by Adam, and death entered by sin. This was the legacy which Adam left to all his posterity.
Now the sad and mournful truth that the scripture contains is this: “That our first parent, by his transgression, has entailed a miserable inheritance, an unhappy portion of sin and death upon all posterity.” Adam’s sin becomes ours.
1. By meritorious imputation: God treated with him not as a private person, but as caput gentis, as the root and parent of all mankind.
Hence a comparison is often made between the first and second Adam; the grace of the one, with the sin of the other: the life conveyed by the one, and the death transmitted by the other.
By Adam we were cast, by Christ we were cleared; cursed in Adam, crowned in Christ. Now this comparison would be wholly insignificant if Adam had not been looked upon as the representative of us all.
2. The sin of Adam is derived to us by way of inhesion: We have received from him a depravity of nature, an evil disposition, a propensity to all mischief, and aversion to all good.
The sin of Adam transmitted to us, does not only cause guilt upon our persons, but filth upon our natures; not only lay a charge to us, but throws a stain upon us.
3. We make Adam’s sin our own by imitation, by treading in the steps of his disobedience. Every sin we commit in defiance of the threatenings of God is a justifying of Adam’s rebellion against God; and accordingly, we die by our own folly, as well as by his fall; our destruction is of ourselves, by our actual rebellions; and we shall at the great day charge our sin and misery upon ourselves, not on God, but on Satan, not on instruments, not on our first parents.