If you really care about Jewish identity, you need to care about the observance of Jewish law.

This sounds like a modern slogan from a frum outreach organisation — but it actually belongs to the first century Jewish historian, Flavius Josephus.

Josephus is best known for his account of the Roman conquest of Jerusalem in 70 CE. But one of his lesser known works, Against Apion, is a remarkable defence of Jewish identity. Greek scholars argued that Judaism was of recent origin and had borrowed ideas from others around it. Josephus bravely set out to prove that it was of far greater antiquity than the religious traditions observed by the Greeks themselves.

In this work, Josephus stressed above all the centrality of knowledge and observance of Jewish law to the People of Israel. He argued that Jews are uniquely commanded to regularly study their laws, to the extent that, “if anybody do but ask any one of them about our laws, he will more readily tell them all than he will tell his own name”.

Josephus was no fool. He knew that stressing the distinctiveness of Jewish peoplehood or their special cuisine wouldn’t protect Judaism from challenges of cultural misappropriation. Only the extensive system of laws contained in the Torah, lovingly protected and handed down from generation to generation, could truly define an exclusively Jewish identity.

The extraordinary thing about Josephus’ argument is that little has changed in the last two thousand years. Over this time, many people have tried to come up with other ways of defining Jewish identity which circumvent that close bond between the People of the Book and its Book. But, without exception, every single one of them has failed to endure.

This can be measured in a very simple way. Of all the factors that contribute to the assimilation rate in the Jewish community or the proportion of the next generation of Jews who will not be halachically Jewish, there is only one which has consistently had the ability to counter, and even reverse, that rate. This is knowledge and observance of Jewish law. Simply put, if you are observant of Jewish law, your children are exponentially more likely to marry Jewish and continue the Jewish traditions of their ancestors. If you are not, they may well still opt to do so, but there is far less of a guarantee that this will be the case. And the more religiously observant you are, the greater the chances of your children remaining connected to their heritage.

To be sure, there are plenty of ways Jewish people identify with their Judaism, many of which have resounding positive effects across the community. But ultimately, the long-term future of the Jewish community in this country largely depends upon its overall commitment to the observance of Jewish law.

According to recent JPR research, around 53% of those raised in secular or cultural British Jewish households currently choose to marry Jews. By contrast, 93% of those who were raised in religiously-observant Orthodox, and almost 100% of those raised in Charedi, households do so. So, whether we identify with an observant lifestyle or not, we cannot ignore the fact that Jewish identity is inextricably tied to faithful observance of its laws.

This isn’t about scaremongering, favouritism or judging others. People will always make their own choices in life. But it does mean that the community at large should attempt to support, rather than constantly criticise, those who will guarantee the stability of the British Jewish community over the next century.

Let me be clear. Like every other sector of the community, they sometimes get things wrong — and we should always call out wrongdoing wherever it occurs without favour, rather than seek to brush it under the carpet.

But far too many disproportionate and unnecessary attacks have been launched on this segment of the community of late. I, for one, find the gleeful satisfaction in some quarters over recent Charedi anxiety at the proposed new regulations of independent school standards particularly distasteful. Before criticising, think twice about what observance of Jewish law means to you.

I suspect that there are many who do not personally consider religious observance to be a significant factor in their own lives yet care passionately about the future of the Jewish people. So, when they, like Flavius Josephus, attempt to define, defend and preserve Jewish identity from those who wish to question its future, they would do well to respect the central role of those who study and observe the Law in guaranteeing that future.