All things considered, I have come up with my own definition of what a cult is: Any destructive relationship or system in which one party exerts power over another party through undue influence, resulting in harm to the party being controlled . . . Let's examine this definition. 

Defined as a System 
It is important to recognize that cults are systems. It is not sufficient to define them simply as groups, because cults rely heavily on relationship in order to work . . . I feel groups themselves don't necessarily require relationship. Ten people in a room constitute a group, but do not constitute a relationship. Thus, we cannot simply label cults "groups" because not all groups contain relationships. In the same fashion, it is insufficient to simply limit all considerations of systemic relationships to groups. Relationships exist in the context of other systems which are not necessarily groups. 

Personal relationships are systems as well, and therefore can technically be defined as cults if they meet the above criteria. Destructive personal relationships can exist between two people where one person exerts control over another person through undue influence (many unhealthy marriages, especially those involving domestic violence, operate this way). Such personal relationships share the same dynamics as cults and therefore can be described as cults based on my definition. However, because of popular conceptions and professional consensus over what a cult is, (i.e. that cults are largely group phenomena) I will refrain from labeling any personal, one-on-one relationships as cults. Instead, I will describe any such destructive relationships as being cultic, that is, they possess the same qualities as a cult, and yet are not necessarily a cult per se. Conversely, the term cultic can also be applied to any system, especially any group, which shares the same characteristics of a cult but is not overtly destructive. A good example might be a college fraternity. 

Larger systems, such as global movements, are similar to personal relationships in that they can possess the same characteristics as cults, but not be perceived strictly as such. Larger systems are also tricky because the concept of relationship weakens as the system grows. Hitler's Nazi Youth and bin Laden's Al Qaeda are prime examples of larger, more global systems that can be defined as cults. However, larger systems such as these are fundamentally based on the individual's relationship to a social issue rather than to another person.  As a result, these systems will often utilize smaller systems within the larger system to create strong interpersonal bonds. For example, the leader might employ the use of self as a way of compensating for this lack of relationship by making himself or herself out to be an ideal or role model. In any case, the fact that a relationship exists between a person and an idea is not inconsistent with characteristics previously assigned to cults by sociologists. Even in smaller systems, members can be simultaneously devoted to both an idea or concept as well as to the leader or to other members. When appropriate, these systems are often referred to as ''movements." Movement is somewhat of an acceptable term because of the relationship which exists between the members and an idea. But not every cult is a movement. This brings us back again to the idea of using the term system when describing cults, as opposed to using terms like group or movement. 

Defined in Terms of Destructiveness and Undue Influence 
The second qualifier in this definition is that the existing relationship within the system must be destructive. Every system is comprised of relationships, but not all are destructive. Families, for example, are systems that operate on relationship and exist for support. They are generally intended to be nurturing relationships, and the motivation behind such relationships is not to abuse power with the intent to harm. It also should be noted that much of this power is attained through undue influence.

Furthermore, not every relationship which utilizes undue influence is destructive, either. Families have been known to contain relationships in which one party (the parents) exerts control over another party (the children), and sometimes this is done through undue influence. The use of undue influence in such cases is not necessarily harmful to the child. (Many a parent has gone through great pains to unduly influence their children into eating their vegetables or brushing their teeth before bed.) Therefore, undue influence by itself is not necessarily a characteristic of a cult. When undue influence is combined with destructiveness and inflicted deliberately for the purposes of furthering harmful manipulation or deception, it then becomes a characteristic of a cult. 

Diagnostic Criteria 
I believe my definition is not only all inclusive, but exhaustive in that it is also exclusionary where appropriate. Moreover, I am in complete agreement. . . that labeling a cult is a highly subjective process. It is for this reason I would like to go one step further and reject the term, definition. A definition is a delineation with clear boundaries. It is an exact meaning. The process of defining cults  . . . is not an exact science. In truth, it is more of a diagnosis. Cults are identified through signs and symptoms, not by assigning classifications which are based on constants. Much like certain psychiatric disorders such as schizophrenia, cults must be diagnosed. 

Although somewhat tongue-in-cheek, I have provided a hypothetical list of diagnostic criteria for identifying a cult, based on and including the most common contributions by notable scholars on the subject:

A. Characteristic symptoms: A system in which there exists a relationship where one party exerts control over another party through undue influence, resulting in harm to the party being controlled, and two (or more) of the following, each present for a significant portion of time during a 6-month period:

1. Rigorous group mentality
2. Intolerance of outsiders
3. Belief that group, its leaders, and members are above the law
4. Use of undue influence to control members
5. Very little, if not, no room for individuality
6. Controversial reputation in the media
7. Distinct leader/follower relationship present
8. Maintaining control by enforcement of the BITE model: (Behavior, Information, Thought, and Emotion) 
9. Use of deceptive recruitment techniquesI
10. Standing requirement to recruit new members

B. Social/occupational dysfunction: For a significant portion of the time since the onset of membership, one or more major areas of members' functioning such as work, interpersonal relations, or self-care are markedly below the level achieved prior to the onset.

C. Duration: Continuous signs of the disturbance persist for weeks, months, oryears, depending on the severity. This period must include those symptoms met Criterion A.

D. Substance/general medical condition exclusion: The disturbance is not due to the direct physiological effects of a substance ( e.g., a drug of abuse, a medication) or a general medical condition.

Subtypes: 

Religious Type 
A type of cult in which the following criteria are met: 

• Led by self-proclaimed "messiah" or "prophet" 
• Fronts itself as a new religion or improvement of an existing one
• Member preoccupation with spiritual belief system, dogma, or religious practices
• Unorthodox interpretations of holy writings to justify group practices
• Intolerance of other religions  

Political Type
A type of Cult in which the clinical picture is dominated by at least two of the following:

• Presented as an oppressive dictatorship or regime​
• Abuse of power Control of the press 
• Prevention of free assembly and elections​
• Terrorism 
• Suicide Bombing 

Psychotherapy Type 
A type of Cult in which the following are prominent:

• Unethical practices by self-proclaimed "therapist" 
• Lack of professional mental health credentials by the leader 
• Outrageously high fees charged for services 
• Personality tests and psychosocial history of members are used to justify practices

Commercial Type 
A type of cult as indicated by the presence of the following:

• Preoccupation of members to get rich quick 
• Pyramid or "Multi-level" organizational structure 
• Infiltration of legitimate business by questionable "consultants" 
• A consensus of derogatory feelings toward honest means of making a living

Undifferentiated Type 
A type of cult in which symptoms that meet Criterion A are present, but the criteria are not met for the Religious, Political, Psychotherapy, or Commercial Type. An example of an undifferentiated type would be a group dealing with flying saucer or other outer space phenomena. I would also use this category to include any highly controlling personal relationship, such as those between abusive spouses and their victims. Some systems have similar or even the same symptoms. The "clinician," therefore, in his/her diagnostic attempt has to differentiate against other possible explanations which he/she needs to rule out to establish a precise diagnosis. 

Guerriero, J. (2022, June 5). What is a Cult?  Guerriero's Diagnostic Criteria. The Poisonous People Press. https://www.https://poisonouspeople.com/blog/guerriero-criteria