Korea is one of the countries having a lot of different cults or sects connected to the Christian religion. There are countless cults in Korea with so much different ways to interpret the Christian religion than this can even go to very dangerous and illegal acts.
These cults have so much importance that they were responsible of the outbreak of COVID-19 like the « Shincheonji Church of Jesus » with 300 members declared with it. 
This cult is also the biggest one in the history of Korea with a number of 317,320 members. It was created on march 14, 1984 by Lee Man-Hee. This Church has a lot of accusations like some members trying to convert other koreans or foreigners by pretending they are just showing their religion and culture.
Some of them are really weird or even funny :
•    The guns of god : the church where we pray with AR-15 rifles https://www.youtube.com/watch?v=-w2kSlpXjng
•    An unification church doing a wedding of more than 4,000 couples and even 20,000 
online at the same time ! ( extract of the wedding : https://youtu.be/XVchwW9Hw80)
•    Pastor Shin Ok-ju arrested for beating her followers to get rid of their sins.  
And there is even more and different cults like that.