In the world of the show The Walking Dead, an airborne virus has spread throughout the earth and has become part of the surviving humans. The virus becomes fully active once a person dies and they become zombified, a reanimated corpse. One can imagine a zombified person to itself is the most free. It is free of many of the things that make us human. Free of responsibility, free of emotion, free of law and order, among other things. It can focus solely on its desires.
Sin is like that virus, in which once a person dies spiritually it takes hold and transforms that person in similar fashion. Sin, like that zombie virus is relentless, indiscriminate, and all consuming. Those that have been given over to sin can see things the same way. Free to do as one's heart desires, without fear. However, those who are on the outside (survivors if you will) see things with a much different perspective. They can see how that "freedom" is more of a bondage and how destructive it is to the host and