German rabbi who became a founder and leader of radical Reform Judaism. His theological positions were radical even within the Reform movement.

From 1836 to 1840 Holdheim officiated as a rabbi at Frankfurt an der Oder. In 1840 he went as Landesrabbiner (rabbi of a whole province) to Mecklenburg-Schwerin. Three years later he published his controversial and important book Ueber die Autonomie der Rabbinen (“The Autonomy of the Rabbis”). In this work he concluded that Jewish marriage and divorce laws were obsolete because they represented the national aspect of Judaism (no longer valid) as against its enduring religious aspect. Such laws, he held, should be superseded by the laws of the state, for Judaism is a religion only, whose essential core is to be found in biblical ethics and doctrine. During the rabbinical conferences of 1844–46, which elaborated the ideology of Reform Judaism, Holdheim played a dominant role.

In 1847 he became rabbi of the Jüdische Reformgenossenschaft (“Congregation of the Jewish Reform Alliance”) in Berlin, where, for Reform Jews, he established Sunday as the day of worship and, except for Rosh Hashana (the Jewish New Year), abolished keeping the second day of holidays. Holdheim's writings form part of the classical literature of Reform Judaism, although few of his ideas are generally accepted within the movement today.