Westminster Shorter Catechism
Quest. 16. Did all mankind fall in Adam’s first transgression?
Ans. 16. The covenant being made with Adam, not only for himself, but for his posterity; all mankind, descending from him by ordinary generation, sinned in him, and fell with him, in his first transgression. Gen. 2:16-17; Rom. 5:12; I Cor. 15:21-22.
Quest. 17. Into what estate did the fall bring mankind?
Ans. 17. The fall brought mankind into an estate of sin and misery. “Rom. 5:12.
The point that we wish to emphasize here is that the very representative principle which brought death and condemnation to all men is also the means of bringing eternal life. Let us not cherish enmity, then, against God’s dealings with us in Adam. Let us acknowledge that God has done that which is right and good (even though we do not fully understand it).
And let us above all make sure that we heartily embrace the offer of God’s free grace in Christ, and cast ourselves upon His representative work that we might be saved.
In any case: we accomplish nothing in objecting to Adam’s representation.
The fact remains that we are guilty, sinful, and miserable (by nature). Explain it, or explain it not, as we may, it remains true.
It is also a fact that there is no other salvation for such sinners as we are, except by the work of Jesus Christ as the representative of His people.
And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat:But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.
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:
1 Cor. 15:21-22
For since by man came death, by man came also the resurrection of the dead. For as in Adam all die, even so in Christ shall all be made alive.
(G.I. Williamson, The Shorter Catechism. vol. 1).