It is counter-productive to tell anyone they are in a cult and Jehovah’s Witnesses reject such a notion.
1: a religion regarded as unorthodox or spurious …
3: a system of religious beliefs”
merriam-webster.com/dictionary/cult (20 Aug 2018)
The definition of “cult” encompasses all religious groups, but the word “cult” conjures images of communes, rituals, a charismatic leader, and followers ready to kill or die for their cause. With such a broad range of meaning, using “cult” in conversation leads to disagreement. In popular culture, cult is commonly used as an insult, and hence describing a person’s religion as a cult will alienate them, preventing intelligent discussion about the merits of the group.
More pertinent is to identify whether a religion is “high-control,” manipulating followers through “undue influence” or “coercive persuasion.” Groups become destructive when using high levels of control to enforce harmful choices regarding issues such as education, finances, medical treatment and associates.
In the 1950’s Robert Lifton conducted groundbreaking research into control techniques to identify how the Chinese government had been able to convince captured American pilots to accept Communist ideology.  Lifton outlined eight thought reform techniques that form a basis to identify religions using coercive persuasion to control followers, of which all eight are utilized by Watchtower leaders. These eight points can be summarized as follows; the leaders of high control groups demand they must not be questioned because a mystical source of guidance makes them the sole channel of truth and salvation. Members must separate themselves from the world and face punishment if they leave. This is the very core to Watchtower doctrine, which purports that Jehovah directs Watchtower’s leaders, the faithful and discreet slave, who must be followed for a person to survive Armageddon. Jehovah’s Witnesses must separate themselves from the world, and those that stop following Watchtower rules are disfellowshipped and shunned.
See footnote  for a description of each point, along with Watchtower examples.
Steven Hassan  is a renowned cult specialist who labels a group as unhealthy if it uses control techniques to keep followers dependent and obedient. His BITE model outlines control across four categories.
Regulation of an individual’s physical reality. A major commitment of time is required for group meetings and activities. Obedience to rigid rules encompassing areas as diverse as morals, appearance, entertainment and education is enforced.
Information generated by the group is used extensively, which can be distorted with rhetorical fallacies, or include outright lying. Information is withheld from members. Studying information produced external to the group is discouraged, particularly if it contradicts the groups beliefs, is critical of the group, or is from former members.
The group’s doctrine must be internalised as “Truth,” with no critical questions about the leaders or doctrine seen as legitimate. Black and White thinking is promoted, categorising things as good or evil, us or them.
Excessive use of fear and guilt is used as a means of control; such as fear of “worldly people,” fear of being shunned by the group, and fear of losing salvation. Phobia indoctrination inculcates irrational fears about questioning the leader’s authority or leaving the group. The person under mind control cannot visualize a positive, fulfilled future without being in the group.
Prior to joining, it is difficult to comprehend the extent of control a group wields, and after joining, by their very nature they become accepted as justifiable. Fortunately, there is a simple test to identify any group as unduly controlling before joining. Hassan advises that the first question a person should ask any group is,
“Does your group impose restrictions on communicating with former members? This is one of the most revealing sets of questions you can ask any cult member. Any legitimate organization would never discourage contact with former members.” Combating Cult Mind Control p.109
Likewise, Eliyahu Federman writes,
“The distinction between cult and religion lies squarely in how those leaving or those wanting to leave are treated.” 
Watchtower enforces strict shunning of those that leave, particularly if they have been formally disfellowshipped. This is not an uncommon practice, as around 1 percent of Jehovah’s Witnesses are disfellowshipped each year. Whilst Jehovah’s Witnesses align closely with all of Lifton’s and Hassan’s criteria, the strict emphasis on shunning former members is enough to identify the Watchtower as a destructive, high-control religion.
Being one of Jehovah’s Witnesses can be enjoyable, due to the strong sense of community it offers, and hope of future paradise. Yet at its core, Watchtower is a fear based doomsday religion that believes itself to be the special focus of an interdimensional battle that will soon result in Satan turning government forces against them.
Image Source: Pure Worship of Jehovah – Restored at Last! (2018) pp.196-197
Whilst Watchtower proudly promotes the unity of its members, rigid conformity is a disturbing sign of excessive control, particularly because unity is enforced through the threat of being disfellowshipped from the group.
To refer to Jehovah’s Witnesses as a cult is likely to be met with scepticism by members of both the religion and the public. What is clear is that the members are exposed to excessive levels of control. This results in negative outcomes, such as when members forgo pursuing an education and career of choice due to the century long false promise that the end is within a few years. The control its leaders have ensured shocking teachings are followed, such as not reporting the abuse of children, wives remaining with violent husbands and members dying after refusing blood transfusions. For those that no longer accept Watchtower teachings, there is no easy way out. They face a future of ostracization, even by their closest family, an appalling practice that results in depression and even suicide.
Watchtower teachings, how they are enforced and the effect on followers lives have resulted in Jehovah’s Witnesses being listed on cult watchlists and a general consensus amongst experts that Jehovah’s Witnesses are subjected to an unethical level of coercive persuasion.
 Thought Reform and the Psychology of Totalism: A Study of “Brainwashing” in China. 1961
 Lifton outlined the following 8 criteria that identify groups using coercive behaviour. I have included Watchtower quotes as examples of each point.
1. Environment Control
Limiting communication from outside the group, including written information and friendships with non-believing family and friends.
“False religious propaganda from any source should be avoided like poison!” Watchtower 1987 Nov 1 p.20
“We must also be on guard against extended association with worldly people. Perhaps it is a neighbor, a school friend, a workmate, or a business associate.” Watchtower 1994 Feb 15 p.24
2. Mystical Manipulation
The group has a higher purpose and special calling.
“In effect, Jesus also conveys Jehovah’s voice to us as he directs the congregation through “the faithful and discreet slave.” (Matt. 24:45) We need to take this guidance and direction seriously, for our everlasting life depends on our obedience.” Watchtower 2014 Aug 15 p.21
3. Demand for Purity
Followers are told they are identifiably better to the world around them because of the change the groups rules has on them.
“The resulting peaceableness of Jehovah’s people makes them a refreshing oasis in a violent world.” Watchtower 2002 July 1 p.17
4. Cult of Confession
Confession of sins, doubts or critical thoughts about the integrity of the leaders is expected.
“It is certainly not easy to confess to others deeds that one feels ashamed of and to seek forgiveness. It takes inner strength.” Watchtower 2001 Jun 1 p.31
5. Sacred Science
The group’s perspective is absolutely true, explains everything, and absolute conformity to the doctrine is required.
“First, since “oneness” is to be observed, a mature Christian must be in unity and full harmony with fellow believers as far as faith and knowledge are concerned. He does not advocate or insist on personal opinions or harbor private ideas when it comes to Bible understanding.” Watchtower 2001 Aug 1 p.14
6. Loaded Language
The group develops a vocabulary with loaded terminology and clichés that prejudice critical thinking, replaced with a black and white mentality confined to the narrow parameters of its’ doctrine.
Watchtower assigns common terms with unique meaning specific to the group, such as; pioneer, the truth, new system, worldly, bad association, disfellowship, apostate, organization, slave, theocratic and remnant. Black and white thinking prevails, such as that you are either on the side of Jehovah or Satan, and there is no middle ground regarding topics such as abortion, homosexuality, drugs and religious ideologies.
7. Doctrine over Person
Pre-group and group experience are interpreted through the absolute doctrine, even when experience contradicts the doctrine.
“The world is filled with unhappiness, and people generally have a gloomy outlook on the future. However, we have a bright outlook, knowing that one day all sadness will be a thing of the past.” Kingdom Ministry Feb 2002 p.1
8. Dispensing of Existence
Salvation is possible only in the group. Those who leave the group are doomed.
“An even greater mistake would be to allow the faults of others to stumble us and cause us to leave Jehovah’s organisation. Were that to happen, we would lose not only the privilege of doing God’s will but also the hope of life in God’s new world.” Watchtower 2016 Jun study ed pp.26,27
 For information on Steven Hassan see his official website at https://freedomofmind.com/ and books Combating Cult Mind Control (Park Street Press 1990) and Releasing the Bonds (Freedom of Mind Press 2000)
 When Organized Religion becomes Bad huffingtonpost.com sited 27 Sep 2013
 “In recent years disfellowshippings worldwide have been approximately 1 percent of publishers.” Watchtower 1992 Jul 1 p.19