Ron Rhodes, The Challenge of the Cults and New Religions: The Essential Guide to Their History, Their Doctrine, and Our Response (Grand Rapids: Zondervan, 2001), 31–34:
SOCIOLOGICAL CHARACTERISTICS OF CULTS
I noted previously that even though cults should be defined from a theological point of view, we can nevertheless gain valuable insights into certain aspects of the cultic mentality from sociology. . . .
 Authoritarian Leadership
Authoritarianism involves the acceptance of an authority figure who exercises excessive control on cult members. As prophet or founder, this leader’s word is considered ultimate and final. . . .
Often this authoritarianism involves legalistic submission to the rules and regulations of the group as established by the cult leader (or, as in the case of the Jehovah’s Witnesses, submission to the Watchtower Society). Cult members are fully expected to submit, even if they do not agree with the requirements. Unquestioning obedience is compulsory.
Cults often believe that they alone have the truth. The cult views itself as the single means of salvation on earth; to leave the group is to endanger one’s soul. . . .
The more extreme cults sometimes create fortified boundaries, often precipitating tragic endings (we have already mentioned the tragedies in Waco and Jonestown). Some cults require members to renounce and break off associations with parents and siblings. . . .
 Opposition to Independent Thinking
Some cultic groups discourage members from thinking independently. The “thinking,” as it were, has already been done for them by the cult leadership; the proper response is merely to submit. . . .
 Fear of Being “Disfellowshiped”
It is not uncommon in cults that people are urged to remain faithful to avoid being “disfellowshiped,” or disbarred, from the group. Again, the Jehovah’s Witnesses are a prime example, for a person can be disfellowshiped merely for questioning a Watchtower doctrine. . . .
 Threats of Satanic Attack
Finally, some cults use fear and intimidation to keep members in line. Members may be told that something awful will happen to them should they choose to leave the group. Others may be told that Satan will attack them and may even kill them, for they will have committed the unpardonable sin. Such fear tactics are designed to induce submission. Even when people do muster enough courage to leave the group, they may endure psychological consequences and emotional baggage for years to come.
Sadly, some Christian groups share these characteristics to some degree.
Related (update on 3/31/2017): Here’s my attempt to explain how to interpret and apply the Bible: