Zombies are dead bodies with no souls, created by the black magic of voodoo sorcerers. Voodoo is a religion which originated in West Africa and was brought to Haiti in the early 16th century by West African slaves. The slaves could not practice their religion openly and were forced to adopt in public the practices of the French Catholic settlers. Voodoo is still a popular religion in Haiti and in cities where Haitians have emigrated, such as New Orleans. Vodu is an African word meaning spirit or god. The black magic of voodoo sorcerers allegedly consists of chemicals, various poisons (perhaps that of the puffer fish) which immobilize a person for days, as well as hallucinogens administered upon revival. The result is a complacent, paralyzed, or brain damaged creature used by the sorcerers as slaves, viz., the zombies. The zombie is not to be confused with the zombie astral, whose soul (ti-bon-ange) is controlled by the sorcerer.
It is quite understandable that a religion practiced under slavery would emphasize evil spirits. It is a cruel irony that some in the religion would evolve to worship at evil's altar and engage in practices which not only enslave others but keep the community in line from fear of being turned into a zombie/slave.