A cult is a religious organization that takes a sequential approach to total control over individual and group members. The fine line between what appears to be a normal church or temple and a cult is evident in the early stages of recruitment and membership. When the individual is subjected to increasing demands of time, attention, and having the church or temple as the only source of truth in spiritual, then secular matters, a cult like dynamic can bother some people.
Bernie Mac, a great comedian, had an episode of his comedy show where his wife made him show more attention to the church. He pretended to "join" the flock in order to get away for a football game, and found himself in an ever increasing series of intrusions by church members and church leadership. Eventually, church deacons were even showing up at his house, uninvited, to participate in every aspect of his free time. This is an example of the increasing demands that churches are making to insure that members actually invest in the entire set of programs and events that the church offers. In many churches, there are requirements for regular bible study, calls to volunteer at events or in the myriad of "special ministries", in addition to basic worship and financial support.
The fine line is here: when the individual is isolated completely from family, friends, and normal socialization and completely controlled in their living facilities, financial matters, and when the religious leaders control all definitions of truth and reality, then a cult environment exists. In some cases, intensive and personal interaction is aimed at individuals who fully isolate from society and demonstrate that they believe in the organization as the sole source of everything in life.
The behavioral and emotional sources of individual cult immersion lie in the conflict between where the individual is spiritually, and where the individual desires to be. The individual rejects all known and regular church programs and counseling for such conflict, and seeks something completely new and different, indicating that there is some trauma related to past religious contexts. There is simply no trust in the family's religion or in any mainstream religions.
Cult recruiters are experts at seeking out and contacting individuals who are in these states of unresolved conflict, and are masterful at using the conflict to attract the seeker to go through what is commonly described as a deviant process toward a promised form of spiritual enlightenment or resolution. The process is akin to, or maybe identical to brainwashing and includes those control, isolation, and truth management processes that make for successful brainwashing.
To "deprogram" or bring an individual out of the cult process is, as a result, very arduous, legally difficult and often impossible, as cults are equally masterful in protecting their turf, through legal and illegal means which include hiding members in remote or international locations, or using armed resistance.
Cults, are then, a deviant form of religion where healthier options for resolving spiritual conflict are rejected for something that can be quite dangerous and problematic. But it is important to keep an open mind, since many accepted and seemingly normal religious organizations have similar cult like properties, issues and problems.