When I was approached to write a short introductory guide to Judaism, my first reactions were merely practical: could I complete it by the deadline? Were the publishers offering enough money?

Did I know enough to write it without extensive research? And finding the answers to be yes, I accepted the commission without too much thought.

But when I started to write the book, it became clear very quickly that this was a bigger deal than I had first imagined. Because when a Jew sets out to write a book about Judaism targeted primarily at non-Jews, all sorts of questions about responsibility and accuracy are raised. My book could well be the first serious account of Judaism that its readers will have encountered — and for some it may well be the last. Any mistakes or lack of clarity on my part could stay uncorrected forever in readers’ minds.

Against my better judgement, I began to feel like an “ambassador” for the Jewish people. This was ironic as in my other writings I have always argued against the view that Jews should present a wholesome, united front to the goyim. It was strange to feel protective of parts of the Jewish world with which I ordinarily have little sympathy, such as the more extreme versions of religious Zionism. Strange, too, was worrying about the dangers of antisemitic readings of what would ordinarily be relatively innocuous facts, such as the prominence of Jews in many spheres of modern intellectual, cultural, economic and political life.

Then there was the tyranny of the word count. I had 25,000 words to play with, which is not a lot for a diverse, millennia-old people that delight in creating complex rituals, customs and intellectual frameworks. I made my life even more difficult by insisting to the publisher that the book should not just be about Judaism narrowly conceived as a religion, but should also cover history, culture and politics.

What this narrow straitjacket meant in practice was being faced with a constant series of difficult and often bizarre choices as to what to include and what to leave out. There were some enjoyably absurd consequences to this need for concision: Yom Kippur got 25 words but Chanucah 83, not because the latter is more important but because the former is much easier to summarise; I left out Shemini Atzeret completely; I mentioned shatnez (forbidden mixture of wool and linen) but not pidyon haben (redemption of the firstborn); Spinoza got one line but Saadia Gaon got nothing; Sacha Baron Cohen makes an appearance but Jonathan Sacks does not. I can justify all these choices, but I agonised over each one.

Controversial issues were a particularly challenge. How to “do” the modern state of Israel in 3,000 words in a way that does justice to the multitude of irreconcilable narratives? How to “explain” the Shoah in a brief but non-facile way? How to sum up the complex and contradictory evidence for and against Jewish genetic distinctiveness?

Wherever possible, I turned to Jewish jokes to provide concise distillations of Jewishness that were often more eloquent than anything I could write. The gag ‘”Question: How many Conservative Jews does it take to change a light bulb? Answer: We’ll set up a committee?” tells you as much about the slow, deliberative process of halachic decision-making within the Conservative movement as I could, but in a much shorter word count.

I also found that Jewish tradition looked kindly on the limitations of my book. The story of Hillel and Shammai being approached to explain the entirety of Judaism “on one leg” is well known in the Jewish world, but not among the audience for my book. In telling the tale, I emphasised Hillel’s injunction to “go and learn”. Any summary of Judaism, on one leg or in 25,000 words, can only be a starting-point.

I ended the final section of the book with one of my favourite Jewish quotes: “It doesn’t matter what kind of Jew you are, provided you are ashamed of it.” Sadly I could not find a source for it (can readers help?) but I had to put it in. The Judaism that I love is an antidote to smugness — you can never do, think, learn and practice “enough”. This seemed to be an excellent caution and challenge to non-Jews seeking to learn more about Judaism; neither my book nor any one source will ever tell you everything.

There are a lot of short intros to Judaism on the market. This diversity and competition again reminds readers that any one book can never be enough. If everyone has a novel in them, then maybe all Jews have an introduction to Judaism in them.