https://www.mljtrust.org/sermons-online/ephesians-6-10-13/cults/

What are cults? Why are they so dangerous? In this sermon on Ephesians 6:10–13 titled “Cults,” Dr. Martyn Lloyd-Jones says that cults are groups that are not Christian, but nevertheless claim to be. They teach things that fundamentally deny the Christian faith and gospel. Often, cults are centered around one person who claims to have received a special divine revelation. These cults either deny the authority of Scripture altogether, or they put another authority on equal level or above that of the Bible. Many of these cults minimize or deny the doctrines of sin, the incarnation, and the atonement. Unlike heresies, cults are groups that are entirely outside of the church and Christianity. Dr. Martyn Lloyd-Jones says that cults are one of the many ways that the devil deceives people. False teaching can and does destroy people’s lives because it sets them on the path to destruction by denying the true gospel. This is why the church must be clear that the gospel is by faith alone in Christ who is both truly God and man.