The cult, blamed partly for the assassination of late South Korean president Park Chung Hee, is now destroying the political career of his daughter, current head of state Park Geun Hye.
Both Parks were mentored by the late cult leader Choi Tae Min, a Buddhist monk turned Roman Catholic who around 1970 started his own religion called Yongsaenggyo, which means Sect of Eternal Life. It includes various elements of Buddhism, Christianity and a Korean religious movement called Cheondoism, which combines Confucianism and Korean shamanism.
In an advertisement for Yongsaenggyo, Choi described himself as the royal messenger of the spiritual world. He also claimed to be a modern-day Buddha and pastor, preaching that everyone was God in the beginning and should lead a life of salvation so as to become God again and live eternally.
He was also a powerful shaman, according to a 1998 book on him written by Korean cult expert Tahk Myeong Hwan.
In 1974, after Mr Park's wife died taking a bullet meant for him, Choi reportedly approached the family claiming that the dead woman had appeared in his dreams and that he could communicate with her.
He then became a spiritual guide for both Parks and was often compared to Russian cult figure Grigori Rasputin.
However, investigations at the time by the country's intelligence agency revealed that Choi was actually using his connection to the Parks to get bribes.
In 1979, Mr Park was assassinated by his spy chief, who said part of the reason that he killed Mr Park was that the President failed to prevent Choi's corrupt activities and keep him away from his daughter.
But Choi continued to be Ms Park's mentor until his death in 1994. A leaked 2007 report by the United States Embassy in South Korea said: "Rumours are rife that the late pastor had complete control over Park's body and soul during her formative years and that his children accumulated enormous wealth as a result."
Over three years into Ms Park's own presidency, history is repeating itself. Choi's fifth daughter, Soon Sil, a friend and spiritual guide to Ms Park, is now at the core of a corruption and influence-peddling scandal that threatens to ruin Ms Park's career.
It is believed that Yongsaenggyo does not exist anymore, but some of its shamanistic practices may still remain. For instance, Ms Park's inauguration ceremony featured a tree decorated with small pouches symbolising good fortune, which was allegedly Ms Choi's idea.
But Ms Park, in a national address last Friday, denied rumours that she was addicted to a cult and conducted shamanistic rituals in the presidential Blue House.
