How could the Pope have said something so manifestly absurd as he was arriving for his first visit to a continent where Aids has killed more than 25 million people over the past three decades?

He began by saying that the distribution of condoms would not resolve the pandemic, which was fairly uncontroversial. Pope Benedict's motivation for saying so might be metaphysical or moral but few Aids professionals would disagree with the idea. But what could the pontiff be thinking about when he added that, indeed, condoms "aggravate" or "increase" the problem?

Many commentators leapt to the assumption that he was reiterating the wild opinion of the late Cardinal Alfonso Lopez Trujillo, who as head of the Vatican's pontifical council for the family, claimed in 2003 the HIV virus could pass through the latex of condoms. Or perhaps the Pope was referring to the fact that condoms sometimes break, slip or are put on incorrectly.

It is hard to know because the words he used were so vague. When a reporter suggested that the Catholic Church's position on the fight against Aids was unrealistic and ineffective the Pope responded: "I would say the opposite." He cited the importance of the Church's care for Aids victims – the Catholic Church is the world's single biggest provider of care to people with Aids through its hospitals, hospices and orphanages on many continents – and the Church's insistence that sex should be a profound expression of love rather than a hedonistic self-indulgence. On condoms he offered only an aside: "One cannot overcome the problem with the distribution of condoms. On the contrary, they increase the problem."

What seems most likely is that he was suggesting something more tangential: condoms are the product of a culture where sexual licence is acceptable, and this culture needs to be challenged. But his words implied more.

Most Aids campaigners agree the best way to avoid transmission of the virus is to abstain from sexual intercourse or have a monogamous relationship with an uninfected person. That is why the strategy in Africa is the ABC campaign, which stands for Abstinence, Be faithful, and Condoms. But it is no use the Pope sticking to A and B, then implying that C undermines the other two prongs of the attack.

In Africa today, many men routinely seek additional sexual partners and many young women have sex with several older men to provide them with material comforts. It may well be that Africans are no more promiscuous than the rest of the world. But poverty, poor education and the lack of effective health services make the consequences of such attitudes more highly visible.

Abstinence and fidelity may be admirable aspirations but there is a need for other approaches. Condoms have been shown to reduce HIV transmission by 80 per cent. And they are most effective in slowing the disease's spread among high-risk groups such as sex workers and customers, who are perhaps least susceptible to papal obsecrations.

There was a time when it seemed the Church might take a more common-sense view. The retired Cardinal Martini of Milan, who might now be pope had the post become vacant earlier, suggested that in some situations – such as where one partner in a married couple was HIV positive – the use of condoms might constitute "a lesser evil".

But a 200-page report by a panel of scientists and theologians on the subject, commissioned by the Pontifical Council for Health and sent to the Vatican's doctrinal watchdog in 2006, appears mired inside the Curia. Apparently there is too much disagreement about its recommendations which some conservatives feel will be "misinterpreted" by the media and the public.

The trouble is that, when it comes to ambiguous statements that invite misinterpretation, Pope Benedict – to judge by his controversial pronouncements on Islam and his miscalculations over the Holocaust-denying bishop Richard Williamson – does not seem to have that good a track record himself.