"AFRICA is the great 21st-century continent." Thus declares Bob Geldof. With its huge natural resources and a resilient populace, Africa has the ability to outperform China, Japan, and India many times over. And in terms of religion, it has the enthusiasm to evangelise the world.

How one squares these confident assertions with the other picture Geldof presents of Africa in Faith in Africa (Radio 2, Tuesday) - of a continent retreating to religion as a way of "negotiating its way through the terror" of political and economic instability - is one of the contradictions in this two-part documentary. It reflects the central problem, which is that we fail to understand it as a sum of many disparate parts.

One could almost say the word "Africa" has become a logo for a particular group of countries (by no means all of the continent, not even all of sub-Saharan Africa) and a particular set of problems, just as the outline shape of the continent - transformed into a guitar, for instance - has stamped itself on our consciousness as the hieroglyph of Third World poverty.

The contrast between the richly diverse presentations made at the Eden Project by musicians from various African countries for Make Poverty History, and those of fading stars of Western pop at the main venues on behalf of "Africa", intensified a sense of dissatisfaction with the way we talk about the continent. This reviewer is irreparably bothered by this, and Faith in Africa was as a result more irritating than it ought to have been.

This is because there were many admirable things in the programme, not least the fact that Radio 2 dared to schedule two hour-long documentaries on religion, and didn't feel the need to pad them out (as Radio 2 is wont to do) with endless snippets of music.

Few compromises were made to any perceived light-entertainment audience, and Paul Vallely as interviewer provided an excellent foil for the loquacious "Sir Bob".

The world of voodoo, the origins of jazz, and the history of Christianity in Ethiopia were among a plethora of topics discussed. Both men were able to summon up vivid pictures of their experiences travelling the continent together over the past two decades. I look forward to the time when individual African states and their stories are presented with such enthusiasm and panache.

While the geographical centre of Christianity, judged on population, moves inexorably southward - it is now said to lie at Timbuktu - the affluent West continues to develop ways of stemming its own secularisation. It is in this spirit that Opus Dei would like to be regarded, though readers of The Da Vinci Code and the like know it to be a cult of self-mortifying women-haters. As part of its new PR campaign, Opus Dei allowed Simon Cox to investigate; and the result was Club Class (Radio 4, Thursday of last week).

The overall impression he gave was of a movement keen on modernising its practices and, in any case, not half as creepy as it has been made out to be. Only the barbed-wire garters made one wince, and one wonders whether Ruth Kelly, as a "supernumerary" member, sports such an item during tedious Cabinet meetings.