Taleban officials strictly uphold their country's laws
The BBC Afghanistan correspondent, Kate Clark, looks at the tradition of the two great proselytising faiths - Christianity and Islam.
"Go on, go on, just do it, it's only a few words. Go on."
It's a hot, sweaty, mosquito-ridden evening and I'm experiencing the heaviest proselytising of my life.
I feel I now know how people could succumb to brain washing. I'm reduced to the most basic arguments.
"I can't, my Mum would be upset if I became a Muslim. "
"That's alright," came the instant reply. "You can lie to her."
I was shocked. "I can't lie to my mum," I said. "Whatever happened to honouring your parents?"
"Yeah, it would be alright, it would be a lesser sin. Go on, just say those few little words."
Intense pressure
The scene was a small town in south-eastern Yemen, six years ago, in the Hadramuaut region. It's the ancestral home of Osama bin Laden - now a wanted Islamic militant holed up in Afghanistan - but that's not the reason I was there.
Locals boast of having converted Indonesia, Malaysia, parts of India and east Africa to Islam. I could now understand why.
Persuasive tactics
What was making it more difficult was that every conversation I had there was in Arabic - a language in which it's virtually impossible to say the simplest sentence without invoking god.
And it's so easy to convert to Islam - you just make the testament of faith
to a Muslim - that you believe in one god and Mohammed as his messenger -
less than a dozen words in Arabic - and bingo, you've joined the faith.
Arab Muslims have been particularly fond of trying to convert me. When I was working in the West Bank, the first three questions I usually encountered were: "Where are you from?", "Are you married?" and "What's your religion?"
Even friends who are secular occasionally and off-handedly ask when I'm going to convert. One Palestinian friend explained it by saying they believed it was a sure-fire way to Paradise.
Less overt
Afghanistan has been a very different experience. Not because Afghans aren't devout - they're more so if anything. Most Afghans seem to pray and keep the Ramadan fast, but they do it quietly and without much fuss.
Religion seems to come up in conversation, if at all, a long way down the line, when you know people well. And it's never heavy - an exchange of information at most.
But apostasy is one of the severest offences under religious law - a capital crime.
There are very few countries in the world where a death sentence might actually be carried out by the state, but Afghanistan is one of them.
Preaching Christianity
The idea that anyone might choose to go there to preach the gospel is chilling. Yet that's precisely what the workers from Shelter Now International are accused of.
What's ironic is how little sympathy any potential Christian missionary receives in the West in the year 2001.
Possibly in America, still a deeply devout nation, it's different. Interviewers there have asked me lately how it's possible that listening to the Gospel could be a crime.
But generally, it seems that if the Shelter Now employees had been arrested
for being gay or trying to improve women's lives - like carrying out
clandestine literacy classes - there would be far more outrage at
their arrests.
But if few westerners identify with the eight detainees as fellow Christians, their alleged crime makes perfect sense to the Taleban.
They see us foreigners in their own image - likely missionaries, eager to conspire against their faith, ready to line up for Christianity, as they do for Islam.
In this world view, the eight foreigners are just the latest casualties of centuries spent battling for souls by these two great proselytising faiths.
For those brought up in a secular world, the idea of living in poverty as an aid worker seems perfectly reasonable - but being a martyr for the faith seems medieval and utterly incomprehensible.