The trend continues. Synagogue membership figures have been declining for at least a generation, if not considerably longer. Indeed, since 1990, they have fallen by 20 per cent, from about 100,000 member households to about 80,000 today, a loss of 776 on average per annum. Expressed slightly differently, of every five households holding synagogue membership in 1990, one no longer does.

The standard assumption about why this has happened is that one former member has simply lost interest. Judaism no longer compels or engages: time formerly spent in synagogue is now dedicated instead to other more compelling tasks, such as saving the whales, demonising Israel or checking Facebook.

But is this true? Might that former member be doing something else instead? Might there be an alternative explanation?

It turns out that there is, to some degree at least. It’s true to say that they no longer participate in Jewish life. It’s true to say that they no longer make any tangible contribution to our community at all. It’s even true to say that they remain cold in the face of any Jewish communal concern. But the reason for this is not because they don’t care about Jewish life any more. On the contrary, they spend every moment of every day in a Jewish space. The only problem is that the space they spend time in is a Jewish cemetery.

While we have had data measuring the number of synagogue membership households at several points in time over several decades, until now we have never been able to examine that number in proportion to the total number of Jewish households that existed at two or more distinct points in time. These are rather important denominators in any calculations, because they not only tell us the proportion of Jews who hold synagogue membership, they also give us a base against which to assess the reasons behind any decline observed. And it turns out that the decline in synagogue membership seen over part of that generation at least, between 2001 and 2010, can be accounted for not so much by declining levels of engagement, by rather by the declining number of Jewish households in the UK that existed over that period.

Here are the counts. Synagogue membership declined by 4,556 households between 2001 and 2010. But in parallel, the number of Jewish households in the UK also declined, albeit by the slightly smaller number of 3,894. But that is 3,894 households that couldn’t possibly have been in the 2010 synagogue membership counts because they simply didn’t exist any more. Zichronam livracha and all that — I don’t mean to be callous — but we should be at least somewhat cautious in drawing our conclusions about what is happening to Jewish life without taking into consideration how many Jews actually exist.

All of that said, the proportion of Jews in the UK who hold synagogue membership has also declined by a few percentage points over the past decade-and-a-half — from about 59 per cent to 56 per cent — which indicates that mortality is not the only factor. Assimilation, apathy, or perhaps the perceived benefits or costs of synagogue membership, are also involved, albeit not to the extent that the membership counts alone demonstrate. And that suggests that we are simply not doing well enough at encouraging Jews to sign up, or ensuring that they have a sufficiently compelling experience when they do turn up to motivate them to come back afterwards.

The sociologist of religion, Grace Davie, became famous for her description of religion in Britain as “believing without belonging.” Many Christians believe in God, but fewer belong to a church. I always thought Jews behaved in the opposite way: many belong to a synagogue, but fewer believe in God. But if belonging is in decline, and if Jewish believing is often — how should I say this politely — a little parev, that means we’re in trouble.

Belonging to a synagogue matters. More than anywhere else, it is where we encounter Jewish community and find our place within it. News of continuing decline should wake us up, and prompt us to get involved to make our synagogues more vibrant, dynamic and purposeful for everyone. Of course, while we’re there, we can also pray for t’chiat ha-metim — the resurrection of the dead. Just to hedge our bets, you understand. Because that’s the only other way we’ll reverse the trend.

Jonathan Boyd is Executive Director of the Institute for Jewish Policy Research (JPR)