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/
If a person truly read and understood the Bible they'd realize that they are being mislead. Unfortunately, most people get their Biblical education from the leadership and are pretty ignorant of the true meaning of the Bible.
A little bit of laziness, a little bit of “it feels right so it must be right.”
And there is always the desire to embellish on the message with man created ritual and mantra which eventually ends with the message being corrupted with a power structure and hierarchy created. And the longer a church exists, the more corrupted the message gets.
Calling a group a cult does not make it a cult. There are a million Pentecostal churches in the world that adhere to some form of Sondergaard’s teachings. They are not cults. Nor are they cultic.
Nor do false teachings qualify as cultic. The democrat party is drowning in false teachings. It is not a cult. A criminal enterprise, perhaps, but not a cult.