WE ALL know about halal meat; and we may have heard about sharia-approved banking. But what about halal toothpaste, or face cream? And did you know that Krispy Kreme doughnuts are produced in a manner entirely in keeping with Islamic principles?

Halal certification has become a huge marketing trend, aimed at the estimated 1.8 billion Muslim consumers on the planet, many of them young and upwardly mobile. But, as Navid Akhtar explained in The Future is Halal (Radio 4, Tuesday of last week), the impetus for this branding exercise comes not from stern imams, but from savvy, worldly businessmen.

"Halal" implies purity, wholesomeness, and an ethical sensibility. As one commentator put it, halal is a lifestyle choice rather than a religious injunction. And, where there are lifestyles choices to be made, there is also money.

The Department of Islamic Development, in Malaysia, runs the most widely recognised of the certification programmes. Akhtar reported from its recent meeting in Kuala Lumpur, where there were representatives from players such as Nestlé and McDonald's, as well as smaller entrepreneurs, including a company that sells testing kits designed to identify traces of pork and alcohol in your food.

If there was ever an example of the opportunistic relationship between certification and marketing, it is the French perfume company that invited the Malaysians to work with them on a new, halal perfume. The challenge clearly extended beyond simply replacing the alcohol in the product with some other appropriate chemical; for the testers worked with the perfumers at their base in the south of France, and the French admitted that much of the process involved teaching their guests what they actually did.

The frustration of this programme stemmed from Akhtar's reluctance to address this most obvious of issues: was this not just a scam? And would this secularisation of the concept of halal not cause anxiety for those unlikely to want the precedents set by the Prophet applied to washing powder?

Blessedly, we live in a country where, for many a long year, we have not persecuted, let alone burned, anyone on account of their choice of hand cream. Indeed, it was as long ago as 1612 that we last executed anybody for heresy.

The poor, deluded offender was one Edward Wightman - a pub bore, who engaged anybody who cared to listen in disquisitions on how he was the Prophet Elijah. And he might have got away with it, had he not bothered King James I on the subject.

Wightman's tale was told with wit and insight by Andrew Brown and the Revd Professor Diarmaid MacCulloch in a Proms interval talk, Twenty Minutes: The last heretic (Radio 3, Saturday); although why a tale of 17th-century religious intolerance, adorned by the music of Byrd and Gibbons, was thought to be an appropriate way to while away the time between bouts of rigorous modernism is a mystery.

Professor MacCulloch likened Wightman to a modern-day blogger, spouting nonsense to whoever might be out there. Or perhaps like that poor tweeter who joked about blowing up an airport, and then had the misfortune to be taken seriously by the authorities.