There are varying degrees of cultism. But one thing that is common in the extreme examples is when the leadership claim that you need them for your salvation. Oh, and send us money now!
Christ? God? Well I spoke to them and they told me to give the gospel. “I am the path to God.” People are extremely vulnerable to this.
Ask yourself, does your church do this? If it does, then you are a member of a cult.
Cults can have very subtle teachings, which draw in many sincere, Bible trusting Christians.
Cults are common indeed; look at ‘The Last Reformation’, led by Torben Sondergaard, a Danish preacher. They started small, but are now worldwide, with thousands of ‘followers’ in the USA.
A good link of cults:
https://revolutionforjesus.com/2016/06/11/torben-sondergaard-and-the-last-reformation/