The first statue of Kim Il Sung — founder of the North Korean regime and grandfather of current leader Kim Jong Un — was erected on December 25, Christmas Day.

This was no accident: Kim Il Sung was actually a Sunday school teacher and born into a deeply Christian family.

Jonathan Cheng, former Seoul bureau chief for The Wall Street Journal, has spent a decade examining the Kim dynasty, the country's autocratic governance and why its propaganda and society is the way it is.