Cults are formed either at the start of the zombie outbreak or apocalypse or shortly thereafter. They are usually formed by people who believe that the Zombies serve as a higher purpose and are sent by God to purge the world of sin. However some of the cults are formed to create a better world in order to survive the outbreak with the leader as king or queen of the new world.
The cultists themselves are usually people who have experienced the worst of the outbreak and join the leader in order to be spared by Zombies but their leader can manipulate their loyalty to commit inhuman acts such as sacrifices and sadistic rituals. Some cultists may join the cult so that they can avoid being killed by the cult leader or of a general fear of the afterlife.
Cult leaders always use thought reform indoctrination to brainwash their followers into following any command that they are given. Some cults in the apocalypse are not always religiously motivated, but rather a social Darwinism formed society with the strongest being survivors and leaders while the weak are seen as tools to be used. The cultists will show no loyalty towards each other and will happily betray a member in order to gain a higher rank in the cult or they will convince the leader that another member is the best option for sacrifice. Cults will have a strict set of rules and the main punishment for the rule breaker is death by either a murderous ritual or being fed to the zombies
Depending on the type of cult, Cultists will mainly use bladed weapons for combat or sacrifice and as a last resort some members may be brainwashed to believe that they should sacrifice themselves for the cult leader by using explosives. In order to defeat the cult, the leader must be the main target because not all cults will have a second in command and the cult may disband after the leader has been killed.
Not all cults are themed around death and social Darwinism, some cults can be peaceful but will uphold strange but non violent beliefs.
There is at least one cult mentioned in World War Z- a religious sect known as Gods Lambs. They believed that the rapture had begun and that the sooner they were infected, the sooner they would go to heaven. In the video game Dead Rising there is a cult known as True Eye and they believe that they should sacrifice non believers and heretics and that cultists would be spared by the zombies as well as infection for sacrificing others. Another example is Kōichi Shidōu from the anime Highschool of the Dead who became leader of the group of students who survived the zombie attack in the school and manipulated them into sharing his beliefs of the weak not deserving to live and that Shidōu would bring peace for his followers.