How is it possible for the dead to be alive?
There are a number of ways. First, it is entirely possible that a zombie is not actually living dead at all. If a virus existed posessing properties of Rabies and Ebola, the result would be what would appear to be a rotting corpse, bent on biting people, which would lead to the spread of the disease. Humans don’t often suffer from full blown Rabies these days, but it’s not a pretty sight.