“WITH all due respect . . .” When these words are uttered, you can be pretty sure that the next ones are going to be far from respectful. The director of Climate Stewards, Caroline Pomeroy, was talking to Colin Brazier, a Roman Catholic journalist and the presenter of Heart and Soul (World Service, Friday), who has six children. Ms Pomeroy had previously declared that a Christian conscience and concern for the environment prevented her from having more than two children. “I think it’s greedy.” The interview was swiftly faded out. One must assume that it did not end well.

Choosing a presenter so partisan to front a programme of this kind was an intriguing decision. Mr Brazier bookended the episode with scenes from his family life, in which, after the death of his wife last year, the children were not just one another’s companions and competitors, but also counsellors. So embedded are the assumptions about population growth, however — the environmental catastrophe that this growth is bringing down upon us, and religion’s complicity in it all — that it is not unreasonable to allow the other side a head start.

Climate Stewards approaches the environment question from a Christian perspective; in contrast, the eco-charity Population Matters identifies religion as a big part of the problem. And we received the same message, from a lady representing Dandelion Africa, which works with families in Kenya. If you talk to the demographers, however, a different story emerges: of populations which are, in many parts of the world, dipping below replacement rate, and of a global population which will plateau in the next 100 years.

It is not beyond the bounds of human imagination to accept both positions as valid simultaneously. On the question how important a part religion played in all of this, the writer Jonathan Last filed the clinching words of wisdom. The correlation between large families and religion is not, he observed, based on “every sperm is sacred”, but is a much broader one between large families and general religious engagement. Religious parents feel a duty to the past and to the future: they recognise that they occupy “a place in the world which extends out beyond the self, out beyond the present moment”. What Brazier might have acknowledged is that this sense of duty to the future is what also motivates the likes of Ms Pomeroy.

The expectation of first-time motherhood provides the backdrop to Charlotte Runcie’s curious, rhapsodic book Salt On Your Tongue, serialised last week on Radio 4. Wednesday’s episode reflected on the relationship between religion and the sea. Particularly striking was an anec­dote telling of a Victorian murder victim on the Isle of Arran whose boots were removed and buried on the beach even before the police arrived: the niceties of forensic evid­ence were ignored to accommodate ancient custom.