North Korean Choi Kwanghyuk is one of the lucky ones.

The 55-year-old managed to escape from the work camp where he was sent after being targeted and persecuted by the government for his Christian faith.

“We couldn’t raise our voice during a service, we couldn’t sing out loud during a worship … that was hard,” Choi told Fox News through a translator. “Also, we had to hide so that other people could not see us.”

Despite having to hide his faith in plain sight while living in North Hamgyong province, Choi was still compelled to bring religion to others when he started an underground church.

“There were about nine people,” he said. “I couldn’t do mission work because we had to keep it secret that we had a church.”

“If that information had leaked, we could have faced the death penalty.”

North Korea is officially an atheist state where – except for a “show church” in Pyongyang that tourists are shown -- public worship is forbidden. The country is ranked the most oppressive place for Christians in the world and has had that ignominious status for years, according to Open Doors USA.

“[Choi’s] statements describing oppression, as well as his report of imprisonment for owning a Bible or practicing faith, align with everything we know about North Korea,” Open Doors President David Curry told Fox News. “Rated the worst place for the persecution of Christians, North Korea treats Christians horrendously and registers them as 'enemies of the state' for their faith.”

The totalitarian state forces the estimated 300,000 Christians living there to hide their religious beliefs and fellowship among each other.

“In a nation where the ruling regime demands total control over the general public, anything that challenges the government’s power is seen as a threat, including religion,” Jeff King, president of International Christian Concern, told Fox News. “As a result, the North Korean government does everything in its power to squash the spread of Christianity."

This leads much of the religious population in North Korea to go underground with their worship, much like Choi and his church were forced to do.

“We had only one Bible,” he said. “North Hamgyong province is very cold. In the winter, we would dig a big hole and store kimchi there. We sometimes had services there. In the summer, we had services in the mountain or by the river.”

“The life in North Korea is hell. The life in America is heaven.” — Choi Kwanghyuk

“I never heard the term ‘underground church’ until I got here [to the U.S.].”

In 2008, North Korean authorities caught up to Choi and arrested him. He was held in prison by the state security department where he says he was interrogated about his faith.

“I was tortured there,” he said. “I kept denying it.”

He said that he was about to be sent to one of North Korea’s brutal labor camps when he was able to break free.

“I decided to escape because I thought that once they sent me to the other camp, they could eventually send me to the concentration camp or kill me,” Choi recalled. “I was traveling back and forth between China and North Korea, but they kept searching for me, and I knew it could put my friends in danger too, so I left.”

The North Korean gulag system is notorious for harsh conditions and brutal treatment of its prisoners.

Choi feared being sent to the most notorious camp within the system -- Camp 22.

Also known as Hoeryong concentration camp, and part of a large system of prison camps throughout the Communist dictatorship, Camp 22 is an 87-square-mile penal colony located in North Hamgyong province where most of the prisoners are people accused of criticizing the government.

Inmates, most of whom are serving life sentences, face harsh and often lethal conditions. According to the testimony of a former guard from Camp 22, prisoners live in bunkhouses with 100 people per room and some 30 percent show the markings of torture and beatings -- torn ears, gouged eyes and faces covered with scars.

“Unfortunately, it is inexplicably easy to wind up in one of these camps. While someone can be sent to one of these camps for openly evangelizing, someone can just as easily be sent there for simply being in contact with a religious person,” said King of the International Christian Concern.

Prisoners are forced to stand on their toes in tanks filled with water up to their noses for 24 hours, stripped and hanged upside-down while being beaten or given the infamous "pigeon torture” -- where both hands are chained to a wall at a height of 2 feet, forcing them to crouch for hours at a time.

Tiny rations of watery corn porridge leave inmates on the brink of starvation, and many hunt rats, snakes and frogs for protein. Some even take the drastic measure of searching through animal dung for undigested seeds to eat. Beatings are handed out daily for offenses as simple as not bowing down in respect to the guards fast enough. Prisoners are used as practice targets during martial arts training. Guards routinely rape female inmates.

Choi said he finally escaped to neighboring China. While he was figuring out where to go next, he had heard how the general image of North Korean defectors was not positive among those in South Korea.

“So, I applied for asylum in the U.S.,” he told Fox News.

Choi, who was single when he lived in North Korea, was granted asylum in the U.S. in 2013. He first lived in Dallas before eventually moving to Los Angeles where he now lives.

Choi said that as a result of injuries he received while being tortured, he is unable to work but has committed himself to telling the world about the human rights abuses in his native land.

“First of all, every human must have the right to freedom,” he said. “There is no freedom in North Korea. By law, they have the freedom of religion and the freedom of the press, but the reality is very different.”

And despite the hardships he may face, Choi said that life in the U.S. is a vast improvement.

“There is an enormous difference between my life in North Korea and my life in the U.S,” he said.

“The life in North Korea is hell … life in America is heaven.”

Fox News' Inwook Song contributed to this article.