Though Christianity has seen tremendous growth in South Korea the past few decades, North Korea was originally where the Church flourished on the Korean peninsula. This changed when Kim Il Sung became leader of North Korea, all religions were banned and Christians were forced to either renounce their faith or face imprisonment or death. To the masses, Kim Il Sung was God, and with his wife and son, they formed a Juche Trinity.
Today the presence of Christianity in North Korea is bleak. Children are taught from an early age that there is no God and have no concept of any religion. If people become Christian or are simply caught with a Bible, they could be executed. However, North Koreans who have made previous trips into China will tell those going for the first time to seek help at buildings with a cross on them. While those looking for help may not know the actual significance of the cross, it still represents a hope of salvation from the life they face in North Korea.
An In-Depth Look
In the 1940s, Christianity enjoyed tremendous growth on the Korean peninsula, mainly in the northern half. Until 1950, according to some estimates, there were 2,850 churches, 700 pastors, and 300,000 Christians in North Korea. Pyongyang was referred to as the New Jerusalem. But with the end of World War II and the rise of Kim Il Sung to power in North Korea, the Church suffered a major setback. Religion was outlawed in North Korea, causing thousands to flee to the South through the end of the Korean War.
The refugees we spoke with had no concept of God or religion. They were taught in school that there's no such thing as God and had never heard of Jesus. North Koreans have no concept of life after death. They believe that once people die that's the end. Prayer is not taught either. Several refugees we spoke with didn't know how to pray, neither in terms of the words nor the procedure. One refugee said he saw people praying in a movie on North Korean TV, but didn't understand what they were doing.
Though Christianity is illegal in North Korea, there are stark similarities between it and the Juche philosophy indoctrinated into all North Koreans from birth. Instead of the Holy Trinity of Father, Son and Holy Spirit, people are taught a different trinity that includes Kim Il Sung, his mother Kim Jung Sook and his son Kim Jong Il. National laws are also written in a style that resembles Mosaic Law. One refugee who was learning about the Bible for the first time said he had an easier time understanding the Old Testament than the New Testament.
Children are taught to give thanks to Kim Il Sung and Kim Jong Il for their food. Photos of the two adorn the walls of every house as a reminder of who supposedly cares for their needs.
The consequences for taking part in any Christian-related activity can be deadly. After meeting a Christian in China, a refugee we met and her friend took Bibles back to North Korea, despite warnings that they could be killed if caught. They made it back to their hometowns safely and kept the Bible hidden. However the Bible belonging to the friend was accidentally found by some kids, and the woman was taken away never to be heard from again.
Merely saying that you're Christian results in immediate death, according to many of the refugees we spoke with. North Korean defector Hwang Jang Yop, a former confidant of Kim Il Sung, said, "If someone really wanted to attend church, or declared allegiance to it, he would be shot within five minutes."
The government has set up two official Christian churches in Pyongyang, but only for show. Hwang said, "Those that really go there are state-ordered 'believers.'" Knowledge of underground churches is minimal (?). There is also word of anti-government contrabands hiding out in the mountains of North Korea who became believers (how?). Knowledge of these "Christian guerrillas" is also limited.
RESOURCES
Refugee Interview
"All Christians killed... even relatives." (from 6/27/01 interview
with NK woman) 
"Until now... I've never heard if there is a God." (from 6/30/01
witnessing time with NK man who just arrived in China 2 days prior)
"Sharing the gospel with NK refugee" (from 6/30/01 witnessing to
two NK refugees who just arrived in China 2 days prior)
Audio
"Uncovering North Korea - Part 4/5" by NK Guy (Report from the North
Korea Investigative Mission Trip 2001)
Articles
"The Challenge of North Korea Missions" (M. Div. thesis, David Lee)
"Defining a Church Planting Movement" (M. Div. Thesis, David Lee)
"Keeping the Faith Underground" (April 4, 2001, Washington Post)
"Persecution in North Korea" (2001, Voice of the Martyrs)
"The Spiritual Struggle for Korea" (1997, Cornerstone)
"The Church in North Korea" (1998, Cornerstone)