What is the simplest definition of death?
The simplest definition of death is separation. In the physical sense, it is the separation of the body and the soul. Death entered through sin when Adam ate, and passed upon all men because all have sinned. No one escapes it, since all are born of Adam.
Les teaches that death is first and foremost defined as separation. Looking at physical death, which people are most acquainted with, it is the separation of the body and the soul. He explains from verse 12 that by one man, Adam, sin entered into the world, and death entered by sin. Before Adam ate, nothing died; death was an unknown entity. But once he ate, sin came in, and with sin came death. That death passed upon all men, because all have sinned, as Paul says in Romans chapter 3. No one escapes it because we have been born of Adam.