I am very happy to hear this- very happy.
Paul said sin is the transgression of law, where there is no law, there is no sin.
Paul said he was alive once without the law, but when the law came, sin revived and he died.
How could this be? Easy. When he was a child he could not comprehend the law and so was alive. But when he got old enough to understand the law, he became accountable for his sins. Sin revived and killed him.
What law did those from Adam to Moses have? The laws written upon the heart and the conscience. When Adam and Eve ate of the tree of knowledge of good and evil, this is exactly what happened, they gained this knowledge, and I believe this is what caused their spiritual death.
This knowledge of good and evil is passed down, we all have it, though it takes a few years to develop. Children generally begin to understand right and wrong before God as they approach their teens. This is about the time you can see the direction a person will go in life, good or bad.
So those after Adam knew good and evil, read the scriptures. They knew murder, lying, and stealing was wrong, well before Moses and the law came. Therefore they were accountable and died for their sins.