It's not about "sin," it's about the
law, and
transgression of the law (which is sin,
Ro 4:3) and, therefore, subjection to the
law's curse of death..
Where there is no law, there is no sin. (
Ro 4:15) and, therefore,
no curse of death.
And yet, they all died anyway between Adam and Moses when there was no law to transgress, to
sin against.
Of what sin did they die?
They died of the
imputed sin of Adam (
Ro 5:17, 18-19), which
imputed sin of Adam was the
pattern (
Ro 5:14) for the
imputed righteosness of Christ.
Paul is demonstrating the
imputed sin of Adam to all mankind in
Ro 5:12-19, where between Adam and Moses there was
no sin because there was
no law and
no death for its violation, yet they
all died anyway. . .because of the
imputed sin of Adam
(Ro 5:17).
God's imputation of Adam's sin (
Ro 5:14) is
imputation of
guilt, as demonstrated in the
deaths of those between Adam and Moses, when there was no law to transgress and to
incur guilt to
cause their deaths.
Cain was
guilty of Adam's sin by
imputation, as is all mankind (
Ro 5:17), which is why all mankind died between Adam and Moses when there was no
personal guilt of transgression/sin to condemn them to death (
Ro 5:12-19).