There has been concern recently that Christian communities face destruction in parts of the Middle East. But there are other parts of the world where they also have extreme difficulty, with Christian groups often citing North Korea in particular.
You need to be wary of information coming out of North Korea - fellow travellers of the regime in Pyongyang see no evil.
On the other hand, some of those hostile to it have occasionally embellished tales of horror and reported rumour as fact.
So it is impossible to verify the assertion by one group of militant Christians who say that North Korean believers "aren't simply killed for their faith in Christ. They are pulverised with steamrollers, used to test biological weapons, shipped off to death camps or shot in front of children".
There is another view, and that is that Christians certainly have a hard time in North Korea, but they are tolerated providing they don't proselytise.
Keep it to yourself, and we won't be ultra-hard on you, might be a way of putting it.
There are four state-sanctioned Christian churches in Pyongyang - two Protestant, one Catholic and one Russian Orthodox.
To the critics of the regime, they are merely for show.
One person who attended a service at Chilgol Church told the BBC it seemed like a typical Anglican Church, with a small congregation of perhaps 20 people, many of them elderly women, and a choir (which he thought was rather good).
Bibles were bilingual, in English and Korean, and printed in South Korea.
The church, by the way, is dedicated to the memory of Kang Pan-sok - the mother of the first leader of North Korea, Kim Il-sung. She was a Presbyterian named after St Peter (Pan-sok means "rock").
The Christian tradition would not have been alien to the founders of today's North Korean state.
Or take the Pyongyang University of Science and Technology which opened in 2010, which is funded largely by devout Christians from the US and South Korea.
According to one former teacher, many of the teachers there are devout Christians, but the (perhaps unspoken) deal the regime has made is that it gets a very high-grade teaching establishment and the funders and teachers get an "in" into North Korea for whenever the place is opened up.
They feel it is ripe for conversion when the regime changes and they are there for that moment.
Suki Kim, who taught there, said that two colleagues she trusted had told her that a teacher had been deported for handing out scripture.
Overt evangelising was absolutely forbidden but more subtle forms were possible, like using biblical verse as examples of text in language lessons.
Having said all this, the university is a very small and isolated part of North Korean life.
It is not a way of spreading Christianity to the bulk of the people.
The regime seems to fear that Christianity could spread as it has in South Korea and become an alternative power source, certainly an alternative ideology.
There is no doubt that the government in Pyongyang is tough on outsiders who get into the country and distribute bibles.
They are invariably jailed and in some cases sentenced to hard labour in a prison regime which is brutal.
I personally know a missionary who was imprisoned in North Korea and who remains psychologically badly damaged by his punishment - which he will not describe because it was so traumatic for him.
The case of Hyeon Soo Lin
Canadian pastor Hyeon Soo Lim was detained by North Korean authorities in January when he travelled to the country for humanitarian work.
Mr Lim has made numerous trips to North Korea over nearly two decades to distribute food and clothes, his network expanding to become an important conduit for funds donated to the country.
He also helped run a nursing home, a nursery and an orphanage.
The North Korean state news agency KCNA reported last week that Mr Lim had admitted to using humanitarian work as a guise for "subversive plots and activities in a sinister bid to build a religious state".
Astute outside observers think it is possible to be a Christian in North Korea but attempts to convert and turn Christianity into a movement are hammered.
Isaac Stone Fish, the Asia editor of the respected Foreign Policy journal, told the BBC that Kim Jong-un's regime didn't so much have a problem with Christianity in itself - but they do have a problem with a movement which would be a threat to themselves.
James Pearson, who covers Korea for Reuters and is the author of North Korea Confidential, said the state formally "espouses freedom of religion, but effectively bans it".
The services in the few churches in Pyongyang may or may not be fake stages to give a false impression of tolerance (as some of the outside militant Christian groups assert).
It is also impossible to know how many Christians there are underground, hiding their faith from all but their trusted friends and family.
It is certainly true that anybody who wants to prosper in authoritarian North Korea will not get very far if they espouse Christianity strongly.
But there are Christians, some out in the open, affiliated to the state-approved Korean Christian Federation and some unseen and uncounted.
The unapproved Christian groups seem to be at their strongest in the north of the country near the border with China, because missionaries from there can get in and out more easily (though China is uneasy about them too).
One Westerner who had lived in Pyongyang for several years told the BBC that he thought the official Christians he had met didn't seem to have a strong faith. He was continually amazed by how superstitious the people were in all kinds of non-Christian ways and they had no fear of talking.
Unthreatening, unorganised superstition is one thing in North Korea - organised Christian belief quite another.
Hear Stephen Evans' report for the Radio 4 Sunday programme.