If any of the previous verses were unclear, the 19th clarifies Paul’s meaning so clearly that the densest and most skeptical individual ought to understand.  That any man can deny that the Bible teaches the doctrine of federal headship, and the imputation of guilt and righteousness, in the face of this passage, seems to me incredible; yet we know that unbelief leads men into the very greatest contradictions, and compels heretics to twist and contort the word of God as they struggle to make it justify their indefensible positions.

By one man’s disobedience many were made sinners.  The key word here is made: the idea here is that they were constituted, or designated, as sinners.  Our chargeableness with sin is antecedent to any actual sin we may commit, as this passage makes abundantly clear.  We were constituted and charged as sinners, not when we committed our first conscious act of sin, but when Adam disobeyed God and took the forbidden fruit from his wife.  From that moment on, Adam became guilty of sin, and all of his posterity inherited a share in that guilt, his sin being imputed by God to them.  Every soul ever conceived in the womb of woman since Adam is a sinner (save Christ), from the moment the human soul is created by God.  Guilt is charged upon them by an act of divine imputation, and they are subject from that moment on to the penalty of death.