AT 3AM, a thousand young men are all poring over the same page in the Babylonian Talmud tractate of Kiddushin, which deals with definitions of matrimony in ancient rabbinical law. Dressed identically in white button-down shirts and dark ties, the students of Hebron Yeshiva, founded in Lithuania in 1877 and now situated in northern Jerusalem, are observing a millennia-old tradition of learning through the night on Shavuot, which marks the day when Moses received the Torah on Mount Sinai.

This is only slightly exceptional. Any day of the week, save for short holidays, the study-halls at any of the elite yeshivas (Torah academies) in Israel are liable to be packed with students spending as much as 18 hours a day analysing Talmudic texts. Once married, most students will graduate to kollels, smaller institutes where they live off a meagre stipend, government benefits and perhaps their wives’ modest salaries.

For many religious Jews, the flourishing of Torah study in Israel is a fulfilment of the biblical prophecy in Isaiah—“for the land will be filled with the knowledge of the Lord.” For Israeli economists, however, the reluctance of ultra-Orthodox (or Haredi) men to work, coupled with their community’s high birth rate (double the national average), is a problem. A study recently completed by the finance ministry predicts that on current trends Israel’s public debt, currently 67% of GDP,will spiral to 170% over the next 50 years. The ministry says that 45.7% of Haredi men are in the labour force, far less than the national employment rate of 60.4% and lower than for any group except for Arab women (see chart). Haredi women are not expected to study: their participation rate is 71%. According to the Central Bureau of Statistics, the Haredim were just under 10% of Israel’s population in 2009; by 2059 it predicts they will be around 27%. Israel cannot afford to keep paying them not to work.

At the state’s foundation in 1948, Israel’s first prime minister, David Ben-Gurion, accepted the rabbis’ request to be allowed to rebuild the yeshivas which had been destroyed in the Holocaust in Europe. A first quota of 400 yeshiva students was exempted from military service. In 1977 the first Likud government, in which Haredi parties were coalition partners, removed that cap. Successive governments have expanded funding for yeshiva stipends as well as benefits for large families.

The government before the current one included no ultra-Orthodox parties. So the secular Yesh Atid party, part of that coalition, was able to push through a law criminalising draft-avoiders and cutting benefits. The new coalition formed last month by Binyamin Netanyahu as prime minister includes two Haredi parties. These have been promised a repeal of that law and the restoration of benefits to their previous level. The economics ministry, which runs employment policy, and the Knesset finance committee, which has the final say on benefits, are controlled by senior Haredi politicians.

The new economics minister, Aryeh Deri, is the leader of the religious Shas party. He insists he will block any attempt to cut benefits. He blames, instead, Israeli employers who are not interested in hiring members of his community. “There is clear discrimination, even of Haredi men who have studied for law or accountancy degrees. Employers see the black kippah (skullcap), the yeshiva on their CV, and won’t hire them. That’s why so many men remain in kollel.”

Moshe Friedman, a graduate of Hebron Yeshiva who went on to study for nine years in a kollel, echoes Mr Deri. A self-taught software developer, he pitched his digital video-editing startup to Israeli venture-capital funds without success. “Everyone I met immediately asked me, why didn’t I serve in the army and what does a Haredi know about technology?”

Israel’s celebrated high-tech sector, he says, is “a closed ecosystem where people know each other from the army, hire their friends and help them get funding.” He now runs the Kama-Tech programme which works with Haredim on placements with leading tech companies, including the local research centres of Google and Microsoft. But he will have his work cut out: attempts by the previous governments to oblige religious schools for teenagers to teach maths, English and the sciences as well as the Torah have routinely been blocked by religious politicians.