AMERICANS are giving more to charity than ever before—but a smaller proportion of this money is going to religious organisations. Though the amount given to religious charities has risen from an inflation-adjusted $89 billion in 1987 to $105.5 billion in 2013, that represents a fall from 53% to 31% of the total, according to research released by Giving USA, a non-profit that researches philanthropy in America, and the Indiana University Lilly Family School of Philanthropy. There are several possible explanations. One is that religious charities are not as good at fundraising as secular ones. A typical church, synagogue or mosque tends to shy away from having a proper fundraising strategy, says David King, chair of Giving USA’s founding organisation The Giving Institute. Mr King suggests that churches may think of professional fundraising as a “dirty secret” and rely on people to donate out of a sense of spiritual obligation.

Another factor may be that Americans are becoming less devout. The 2013 General Social Survey found that the proportion of Americans with no religious affiliation had risen from 8% to 20% in the previous two decades.

A third—and probably crucial—factor is that the sharp overall rise in charitable giving has been driven by the very rich, who tend to favour secular charities. Billionaires like to give huge sums to art galleries, universities or cancer hospitals, which may then name a wing after them. Church collection plates, by contrast, tend to fill with small donations from average folks. Most religious donations are no more than $40-100, says Dan Busby, president of the Evangelical Council for Financial Accountability, which provides data to Giving USA. Since average folks are feeling squeezed right now, it is remarkable that donations to religious causes have held up as well as they have.