What is meant by cult is fairly straightforward and generally understood, while people define sect in different ways.
How is a cult different from a sect?
Most basically, cults are groups that claim to belong to a certain religion but misrepresent that religion's core teachings in such a way as to prevent salvation according to that religion. Cults usually follows these practices:
• Hides its true purposes and expectations from recruits
• Strictly follows the ideas of one person (sometimes a small group of people)
• Allows the leader(s) to have different rules and expectations than the body of members
• Closely controls the actions of members
Orthodox Christian believers identify any group which teaches and follows heretical doctrine as a cult, such as the Latter-Day Saints (Mormons) and the Watchtower Society (Jehovah's Witnesses).
Steven Hassan, a cult deprogrammer (a person who helps others recover from cult membership) has defined destructive cults using the BITE acronym, explained below.
Behavior Control: A dictatorial, authoritarian leadership controls members' actions, including sleeping arrangements, food, finances, etc.
Information Control: A member's access to outside information is limited, prohibited, and/or distorted.
Thought Control: An "us" vs "them" mentality is instilled and strengthened through a specialized lexicon while critical thinking is discouraged.
Emotional Control: Fear is used as leverage, including shaming, guilt, and threats (including physical, emotional, and spiritual, such as fear of losing salvation or fear of shunning). This is also accomplished through indoctrination.
Cults are dangerous and damaging. A great deal of energy, pressure, and authority are needed sometimes to rescue people from the authority of a cult leader.
Sects are less clearly defined. Sects generally follow established religious faith or a denomination's doctrine, yet differ in minor beliefs. Sects exist in every religion. For example, Judaism has Orthodox and Karaites, Christianity has Baptists and Methodists.
Sometimes sects refer to a group that is seen with disapproval by a more established group, but many times no negative connotation is involved. Sects are also identified outside religion, as in economics where we find capitalists and socialists.
The Bereans, a group of Jews that Paul led to a faith in Jesus, offer us a good example on how to identify and avoid cults and marginal sects: "Now these Jews were more noble than those in Thessalonica; they received the word with all eagerness, examining the Scriptures daily to see if these things were so" (Acts 17:11). We are wise to evaluate any group of which we seek to become a part by gathering the necessary information, talking with those involved (without being coerced by them), and comparing our findings to the truth of God's Word.
What is the definition of a cult?
Is there a good way to evangelize to people in cults or false religions?
What is organized religion and does the Bible support it?
Why are there so many religions?
What is syncretism? How do some people try to blend religious or other thought systems?
Truth about Religion