In North Korea "Christians are classified as hostile and face arrest, detention, torture, even public execution. There is a system of labour camps including the renowned prison No. 15, which reportedly houses 6,000 Christians alone."
World Watch List
"North Korea Remains Worst Persecutor of Christians in WorldICC Note: In North Korea, you, your parents, and your children can be given a life sentence in a prison camp for simply owning a Bible. The North Korean regime remains the most hostile government in earth towards Christianity, and it is estimated that up to 200,000 Christians live in complete secrecy within North Korea."
International Christian Concern
"According to the worldwide report from the non-denominational Christian support group, about 100 million Christians are persecuted around the world, with conditions deteriorating for them most rapidly in Syria and Ethiopia. North Korea topped the survey as the “most nightmarish state” to practice Christianity."