It is one of the great puzzles within the rabbinic world. For years there has been a rising number of British Jews finding non-Jewish partners; at the last count it was 44 per cent of Jews getting married and we may have now passed the half-way mark.
In the past, this has meant at least some of those couples seeking conversion, whether it be out of conviction, for a white wedding, to please the in-laws or have Jewish children.
Of course, there have been lishma conversions too, undertaken purely for the love of Judaism without any partner, but the marriage motive has always been a dominant factor.
But whereas this means there should be a rise in conversions corresponding to the rise in mixed-faith marriages, this has not happened. In the two synagogue movements most open to conversion, the figures have remained static; the average annual number of adult Reform conversions has stayed at 100 for over three decades, while the Liberals - around 60 - currently show a slight decline.
This is astonishing, doubly so given the fact that Reform and Liberal rabbis have made strenuous efforts over the years to make conversion less daunting.
What should count is Jewish upbringing, irrespective of which parent is the Jewish one
In the past it was felt obligatory to dissuade converts - based on Ruth being turned away three times before she was accepted - now we welcome enquiries. The course itself does not make impossible demands, has a time-span of 12 to 15 months and is user-friendly.
This in turn reflects another major change: converts are not seen as an unfortunate concession to be endured, but as a compliment to Judaism to be celebrated. They bring new energy and fresh air. In fact, many religion schools in Reform and Liberal synagogues have a disproportionately high number of converts among the teaching staff.
So why have these changes not had any results and not increased the conversion rate? One reason is the changing social climate. In the past, Britain was largely white and Christian, with Jews being the main minority, with a latent "us and them" culture operating on both sides.
Today, Britain is multi-faith and multi-ethnic, with identities becoming more fluid and relationships crossing boundaries. Mixed marriages are acceptable in society at large, which has influenced the Jewish community too. Couples feel they can be compatible while maintaining separate belief systems. The adage that "the family that prays together, stays together" is no longer held true.
A second reason is that family control has diminished. Young people often leave home and live alone long before getting married, so the influence of parents is much less strong. This is even more so if they reside in another town because of their job and mix in a different social circle. If that once applied primarily to men, it now applies equally to women, doubling the number of young adults living away from home and the vetting of their partners.
A third reason may be self-fulfilling; when the intermarriage rate began to increase, the large numbers meant that it became impossible to write off those couples not seeking conversion. Many synagogues became more accepting of mixed-faith couples - welcoming the Jew as Jewish and the non-Jew as their partner - which in turn lessened the pressure some may have felt previously to convert.
This was seen as a cost that had to be borne. Shooing them away would not have resulted in the Jewish partner deciding to leave the non-Jewish partner, but to leave Judaism. Holding the door open meant they stayed in touch with the community.
The low trend for adult conversions probably cannot be reversed, but what may change is that of minors. There are many mixed-faith families where the non-Jewish partner either has no faith of their own, or does but admires the Jewish lifestyle.
In both cases, they would be happy for the children to be brought up Jewish and to take on a Jewish identity. The Liberals have long held that having one Jewish parent and a Jewish education is sufficient to acquire Jewish status.
Now the Reform has also decided that recognising only the matrilineal line is no longer equitable. Just as the original patrilineal line in the Bible switched in the rabbinic period, because of what was perceived as the needs of the time, so another change is required today. What should count is Jewish upbringing and knowledge, irrespective of which parent is the Jewish one.
Conversion will always be available for adults who wish to pursue it, but it is time to concentrate instead on what is happening to children in mixed-faith homes.
Are we encouraging them to receive Jewish home ceremonies, giving them access to wider Jewish education and making them feel at one with the Jewish community? They have a right to their heritage, while we can benefit from them valuing it.
