as Isaac Mayer Wise, Kaufmann Kohler, Emil G. Hirsch, Joseph Krauskopf, Aaron Hahn, and J. Leonard Levy, with the result that a distinctly panentheistic character of US Reform Jewish theology was observable, which many would have viewed as atheistic or espousing atheistic tendencies. Liberal Jewish theology makes few metaphysical claims, and is thus compatible with atheism on an ontological level. The founder of Reconstructionist Judaism, Mordecai Kaplan, espoused a naturalistic definition of God, while some post-Holocaust theology has also eschewed a personal god. The Jewish philosopher Howard Wettstein has advanced a non-metaphysical approach to religious commitment, according to which metaphysical theism-atheism is not the issue. Harold Schulweis, a Conservative rabbi trained in the Reconstructionist tradition, has argued that Jewish theology should move from a focus on God to an emphasis on "godliness." This "predicate theology", while continuing to use theistic language, again makes few metaphysical claims that non-believers would find objectionable. Secular Jewish culture Many Jewish atheists would reject even this level of ritualized and symbolic identification, instead embracing a thoroughgoing secularism and basing their Jewishness entirely in ethnicity and secular Jewish culture. Possibilities for secular Jewishness include an identification with Jewish history and peoplehood, immersion in Jewish literature (including such non-religious Jewish authors as Philip Roth and Amos Oz), the consumption of Jewish food, the use of Jewish humor, and an attachment to Jewish languages such as Yiddish, Hebrew or Ladino. A high percentage of Israeli Jews identify themselves as secular, rejecting some religious practices (see Religion in Israel). While some non-believers of Jewish ancestry do not consider themselves Jews, preferring to define themselves solely as atheists, some would argue that Judaism is arguably a culture and tradition that can be embraced without religious faith, despite Jewish culture revolving around Abrahamic conceptions of God. Notable people Historically, many well-known Jews have rejected a belief in deities. Some have denied the existence of a traditional deity while continuing to use religious language. Karl Marx was born into an ethnically Jewish family but raised as a Lutheran, and is among the most notable and influential atheist thinkers of modern history; he developed dialectical and historical materialism which became the basis for his critique of capitalism and his theories of scientific socialism. Marx became a major influence among other prominent Jewish intellectuals including Moses Hess. In one of his most cited comments on religion he stated: "Religion is the sigh of the