While true for most, death isn't always the end...
If a god dies, their soul and body are transferred over into The Nothing. A place where all things float and rest. Those who die are conscious, can speak, but can't move much. They also lose all their abilities and chi. If the god dies and goes over to The Nothing, their actual dead body will turn into dust and vanish.
The Nothing is protected by a floating beast, anyone who dares to escape will be hunted down. Escaping this creature is close to impossible. Any other God can enter The Nothing as a living being to free those inside, but just like the ones trapped, they're also followed by the beast. They can grab the 'dead' body and fly as high as possible to exit. If successful, the person will be back to their state before death.
Any individual weaker than a god-like being will die indefinitely and will be given to either heaven or hell. Unlike the gods, their bodies will rot and be buried naturally.
Supernatural indivituals, gods, and those with a certain chi will always come back to life on their own, unless they are killed with a substance or item which is deadly to them. This varies depending on species, blood and origin of the person. If undead, no food, water, sleep or other body functions are needed. Undead have no heartbeat, but can manually create one.
The undead aren't and will never turn into zombie like behaviour. They, their habits and personality are exactly the same before their death, exceptions to this are strong emotional changes such as rage, increase in anger and seeking revenge. Sometimes, those feelings don't go away until its mind is appeased. This most commonly ocurrs in a fight-death.