Basically, like Uncle Sam, Goryeo was having trouble sorting through an equally disorganized religious system.
The country was known as a "museum of world religions" for a reason—so many religions were present that it was almost impossible to keep track of every single one of them. Among those, Buddhism and Christianity were the mainstream faith, while the domestic Cheondoism and cults also had a considerable number of followers.
However, none of those was of much use when the new era began. As it turned out, the ancient Shamanism was the one to save the day.
Shamanistic culture in Goryeo was relatively well-preserved. More importantly, it was recognized as a legitimate religion by the authorities—unlike its cousins in this country who could only carry out their activities underground.
