major Jewish religious thinker and founder of Trennungsorthodoxie (Separatist Orthodoxy), or Neo-Orthodoxy, a theological system that helped make Orthodox Judaism viable in Germany.

Hirsch was a rabbi successively in Oldenburg, Emden, Nikolsburg, and Frankfurt am Main. While still chief rabbi at Oldenburg, he published Neunzehn Briefe über Judenthum (1836; Nineteen Letters of Ben Uziel), in which he expounded Neo-Orthodoxy. This system required two chief courses of action: (1) an educational program that combined strict training in the Torah (Jewish Law) with a modern secular education—so that Orthodoxy could withstand the challenge of Reform Judaism, which interpreted the Torah with the aid of modern textual and historical data; and (2) a separation of Orthodox (Orthodox Judaism) congregations from the larger Jewish community when the latter deviated from a strict adherence to Jewish tradition. In 1876 Hirsch was a prime mover in getting the Prussian parliament to pass a law permitting Jews to secede from the state-recognized Jewish religious community (which Hirsch considered unfaithful to the Torah) and to establish separate congregations. Among his many works are Horeb, Versuche über Jissroéls Pflichten in der Zerstreuung (1837; “Essays on the Duties of the Jewish People in the Diaspora”), an Orthodox textbook on Judaism, and commentaries on the Pentateuch, the five books of Moses (1867–78). In addition he founded (1855) and edited the monthly Jeshurun (the poetic name for Israel). Six volumes of his essays were published posthumously (1902–12).

In one respect, Hirsch's theology was akin to Reform Judaism, in that he interpreted Judaism to be essentially a community of faith; therefore, return to the land of Israel is not necessary for Jewish survival. Unlike the Reform Jews, however, he rejected the application of historical methods to the study of the Bible and of Judaism in general.