The door-knocker told wary punters that she had just come to leave some magazines 'about wildlife'. Not quite a lie, but not entirely the Truth either.

Cutting Edge's film about the Jehovah's Witnesses (Channel 4) began like a recruitment video. You saw the kind of selection-pack of talking heads favoured by party political broadcasts: an engineer in a hard hat, a plumber with his tools, a spruce housewife, a man in a tie sitting in front of a computer, and this fist of Happy Family cards were linked together by a pretty Cuban aerobics instructor going for the burn. "We're modern, we're logged-on, we're not bonkers," this montage seemed to say, "To see what New Jehovah can offer you, send for our free information pack now."

What followed was a touch less promotional in its manner, but it remained scrupulously free of covert sneers or mocking asides. Members of "the Truth" (as they rather disarmingly put it) spoke at the camera, their direct eyeline reinforcing the sense that they were being allowed time to make their case, rather than being forced to defend a collective delusion. When you saw them doorstepping unfortunate householders the deed was filmed from just behind their shoulders, so you were just that bit more likely to sympathise with their disappointment at the unending succession of closing doors. And as they talked of their faith, their faces shone with the kind of unforced conviction for which spin-doctors would sell their souls.

That didn't mean they were convincing, of course. While not a frame in the film encouraged you to laugh (the sole hint of judgement I detected was a line about some believers being "lured in" to the church), there were still places where scepticism could find a roomy foothold. Potential recruits might have been put off, for instance, by the sequence in which the aerobics instructress carried an evening meal out to her fiance, who was sitting in his car outside her house - their only permitted meeting place in case lust should suddenly overcome them. You did wonder, too, how the strenuous disapproval of lying squared with the mild duplicity of the door-knocker who told wary punters that she had just come to leave some magazines "about wildlife". Not quite a lie, but not entirely the Truth either.

Most disconcerting, though, was the blithe conviction that Satan was at large in the world, a sulky hooligan just waiting for an opportunity to dishearten the faithful. Zena (whose daughter Rachel gave the programme an upbeat ending by returning to the church) suspected at one point that Satan might have been fiddling with their car exhaust, but when she told you that Rachel had been bitten by a horse the night before her baptismal examination there was no question that she knew who was to blame. Her face bore a look of amused exasperation that read "Honestly, he's just incorrigible".

I had hoped to review the final part of Auntie - The Inside Story of the BBC, a series which has celebrated 75 years of the BBC by looking at just 64 of them (ignoring the inside story of recent upheavals with a bare-faced audacity that would have impressed a KGB censor). Unfortunately, the tape I received contained an account of the slave trade in Africa. Was this a sarcastic message from disaffected producers within the White City gulag, or was Satan up to his tricks again? And, come to think of it - is there also some coded communication embedded in Back to the Floor, a series in which chief executives return to a menial position in their organisation, the better to understand how the poor sodding infantry are coping with their grand schemes? This was literally the case in last night's programme, in which General Sir Hew Pike took up command of a platoon of soldiers during an exercise on Salisbury Plain. He was hopeless, in an amiable, Geoffrey Palmerish sort of way ("Disorientation is the name of the game right now", he said jovially, shortly after "drowning" half his troops in a river), but made up for it by praising his inferiors to the skies and promising to take up their causes (low pay and shoddy trousers) with his senior colleagues. Not a bad idea really, this bracing immersion in the front-line realities. Perhaps John Birt should volunteer for the next series.