North Korea's Stalinist system is based on total devotion of the individual to an ideology promoted by the late leader Kim Il Sung and his successor, Kim Jong Il. Many outsiders say the ideology largely resembles a religion or cult, and refugees' accounts say those who oppose it are dealt with severely, often ending up in prison camps. Despite the risks, some Christians practice their faith - sometimes with official sanction, often at great risk.
Estimates vary greatly on how many practicing Christians there are in North Korea. Estimates of the number of Roman Catholics range from 2,000 to 40,000. The number of Protestants is also estimated to be in the thousands.
There is only one Catholic church operating in the country. It is the Chan Chung cathedral in the capital, Pyongyang, where more than 100 people attend Sunday Mass, sometimes celebrated by foreign priests who are periodically allowed to visit.
One of those priests, an ethnic Korean from the United States, spoke to a reporter aboard a flight from Pyongyang recently. He says indigenous Protestant ministers but not Catholic priests do live in North Korea. In a bid to prevent eavesdropping by fellow passengers - who likely included a group of North Korean government officials - he converses quietly, and in Spanish.
"We are outsiders, struggling with patience," he said. "We are not allowed to communicate with parishioners. We are only permitted to celebrate Mass, give Communion, but not hear confessions, and most people do not appear to know what confession is. It is hard to explain. It is very sensitive."
Kim Il Sung, the man recruited in 1945 by Soviet leader Joseph Stalin to found the Communist North Korean state, stamped out Christianity and the traditional Buddhism and Shamanism. He installed in their place an ideology resembling a state religion, which rejects any outside influence and which critics say promotes hatred and distrust of outsiders.
That ideology, which preaches self-reliance, is known as Juche, of which the late Mr. Kim is the central figure - so much so that the North Korean calendar begins with the year of his birth in 1912. One of the tallest structures in Pyongyang is the Juche Tower, built in Juche 70, or 1982. Guide Choe Hye Ok explains the ideology to a small group of American reporters.
"Each letter has its meaning, so 'ju' stands for master and 'che' stands for body," said Choe Hye Ok. "So, Juche means 'master of one's self.'"
Belief is mandatory, and the cult of personality surrounding Kim Il Sung is now shared by his son, current ruler Kim Jong Il.
Ms. Choe says she cannot imagine life without Juche, of which she says Kim Jong Il is a prophet. "He is like a father," she said. "Like my father."
Such is the cult of personality that even the facts of the Kims' lives have been altered to fit the official image. Independent outside accounts say Kim Jong Il was born in a Soviet army camp in Siberia, but official history books make people believe he was born on North Korea's venerated Mount Paekdu as a star shone, lightning flashed, and a double rainbow appeared.
Since 1988, the government has allowed state-sponsored churches - three of them - to operate in all of North Korea. Eun Hee Shin is a specialist on Asian religions at Simpson College in the United States, and an expert on Juche. She says official control is overwhelming.
"Kim Jong Il allows Christian churches as long as they follow the party's guideline, Juche," said Eun Hee Shin. "So if there is Christianity, there has to be Juche Christianity. So, it's OK to have Jesus, but Jesus has to be reinterpreted from a Juche ideology point of view."
Religion experts in South Korea say North Korea may also be experiencing something of a Buddhist revival, with some people worshipping at restored temples throughout the country.
The priest who spoke to a reporter on an airplane says it is difficult to discern from people's faces what motivates them to go to church.
"Publicly, they [the government] tell people that anyone who wants to go may go," said the priest. "That is what they say publicly. Those who come are curious."
Little is known abroad about the thousands who missionary groups say are risking their lives by worshipping outside the controlled atmosphere of the state-sponsored churches. Refugees in South Korea say those who are discovered are sent to labor camps where they face torture, starvation and execution.
Over the last decade, Kim Jong Il has allowed Vatican delegations to visit North Korea, mainly to discuss providing emergency food aid to the famine-stricken country by Catholics around the world. Establishment of diplomatic ties with the Holy See, however, does not appear to be on North Korea's rainbow-bedecked horizon.